Methods and apparatuses for forming a three-dimensional volumetric model of a subject&#39;s teeth

ABSTRACT

Methods and apparatuses for generating a model of a subject&#39;s teeth. Described herein are intraoral scanning methods and apparatuses for generating a three-dimensional model of a subject&#39;s intraoral region (e.g., teeth) including both surface features and internal features. These methods and apparatuses may be used for identifying and evaluating lesions, caries and cracks in the teeth. Any of these methods and apparatuses may use minimum scattering coefficients and/or segmentation to form a volumetric model of the teeth.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 15/662,250, titled “METHODS AND APPARATUSES FOR FORMING ATHREE-DIMENSIONAL VOLUMETRIC MODEL OF A SUBJECT'S TEETH,” filed on Jul.27, 2017 now U.S. Patent Application Publication No. 2018/0028064, whichclaims priority to each of: U.S. Provisional Patent Application No.62/367,607, titled “INTRAORAL SCANNER WITH DENTAL DIAGNOSTICSCAPABILITIES,” and filed on Jul. 27, 2016; U.S. Provisional PatentApplication No. 62/477,387, titled “INTRAORAL SCANNER WITH DENTALDIAGNOSTICS CAPABILITIES,” filed on Mar. 27, 2017; and U.S. ProvisionalPatent Application No. 62/517,467, titled “MINIMAL VALUE LIFTING TO FORMA VOLUMETRIC MODEL OF AN OBJECT,” filed on Jun. 9, 2017. Each of theseis herein incorporated by reference in its entirety.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference in their entirety to the sameextent as if each individual publication or patent application wasspecifically and individually indicated to be incorporated by reference.

FIELD

The methods and apparatuses described herein may relate to opticalscanners, and particularly for generating three-dimensionalrepresentations of objects. In particular, described herein are methodsand apparatuses that may be useful in scanning, including 3D scanning,and analyzing the intraoral cavity for diagnosis, treatment,longitudinal tracking, tooth measurement, and detection of dental cariesand cracks. These methods and apparatuses may generate volumetric modelsof the internal structure of the teeth, and/or may include colorscanning.

BACKGROUND

Many dental and orthodontic procedures can benefit from accuratethree-dimensional (3D) descriptions of a patient's dentation andintraoral cavity. In particular, it would be helpful to provide athree-dimensional description of both the surface, and internalstructures of the teeth, including the enamel and dentin, as well ascaries and the general internal composition of the tooth volume.Although purely surface representations of the 3D surfaces of teeth haveproven extremely useful in the design and fabrication of dentalprostheses (e.g., crowns or bridges), and treatment plans, the abilityto image internal structures including the development of caries andcracks in the enamel and underlying dentin, would be tremendouslyuseful, particularly in conjunction with a surface topographicalmapping.

Historically, ionizing radiation (e.g., X-rays) have been used to imageinto the teeth. For example, X-Ray bitewing radiograms are often used toprovide non-quantitative images into the teeth. However, in addition tothe risk of ionizing radiation, such images are typically limited intheir ability to show features and may involve a lengthy and expensiveprocedure to take. Other techniques, such as cone beam computedtomography (CBCT) may provide tomographic images, but still requireionizing radiation.

Thus, it would be beneficial to provide methods and apparatuses,including devices and systems, such as intraoral scanning systems, thatmay be used to model a subject's tooth or teeth and include bothexternal (surface) and internal (within the enamel and dentin)structures and composition using non-ionizing radiation. The model ofthe subject's teeth may be a 3D volumetric model or a panoramic image.In particular, it would be helpful to provide methods and apparatusesthat may use a single apparatus to provide this capability. There is aneed for improved methods and systems for scanning an intraoral cavityof a patient, and/or for automating the identification and analysis ofdental caries.

SUMMARY OF THE DISCLOSURE

In general, described herein are methods and apparatuses (e.g., devicesand systems) for scanning both external and/or internal structures ofteeth. These methods and apparatuses may generate a model of a subject'steeth that includes both surface topography and internal features (e.g.,dentin, dental fillings, cracks and/or caries). Any of these apparatusesmay include intraoral scanners for scanning into or around a subject'soral cavity and that are equipped with a light source or light sourcesthat can illuminate in two or more spectral ranges: a surface-featureilluminating spectral range (e.g., visible light) and a penetrativespectral range (e.g. IR range, and particularly “near-IR,” including butnot limited to 850 nm). The scanning apparatus may also include one ormore sensors for detecting the emitted light and one or more processorsfor controlling operation of the scanning and for analyzing the receivedlight from both the first spectral range and the second spectral rangeto generate a model of the subject's teeth including the surface of theteeth and features within the teeth, including within the enamel anddentin. The generated mode may be a 3D volumetric model or a panoramicimage.

As used herein, a volumetric model may include a virtual representationof an object in three dimensions in which internal regions (structures,etc.) are arranged within the volume in three physical dimensions inproportion and relative relation to the other internal and surfacefeatures of the object which is being modeled. For example, a volumetricrepresentation of a tooth may include the outer surface as well asinternal structures within the tooth (beneath the tooth surface)proportionately arranged relative to the tooth, so that a sectionthrough the volumetric model would substantially correspond to a sectionthrough the tooth, showing position and size of internal structures; avolumetric model may be section from any (e.g., arbitrary) direction andcorrespond to equivalent sections through the object being modeled. Avolumetric model may be electronic or physical. A physical volumetricmodel may be formed, e.g., by 3D printing, or the like. The volumetricmodels described herein may extend into the volume completely (e.g.,through the entire volume, e.g., the volume of the teeth) or partially(e.g., into the volume being modeled for some minimum depth, e.g., 2 mm,3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 12 mm, etc.).

The methods described herein typically include methods for generating amodel of a subject's teeth typically generating a 3D model or rending ofthe teeth that include both surface and internal features. Non-ionizingmethods of imaging and/or detecting internal structures may be used,such as taking images using a penetrating wavelength to view structureswithin the teeth by illuminating them using one or more penetrativespectral ranges (wavelengths), including using trans-illumination (e.g.,illuminating from one side and capturing light from the opposite sideafter passing through the object), and/or small-angle penetrationimaging (e.g., reflective imaging, capturing light that has beenreflected/scattered from internal structures when illuminating with apenetrating wavelength). In particular, multiple penetration images maybe taken from the same relative position. Although traditionalpenetration imaging techniques (e.g., trans-illumination) may be used,in which the angle between the light emitter illumination direction andthe detector (e.g., camera) view angle is 90 degrees or 180 degrees,also described herein are methods and apparatuses in which the angle ismuch smaller (e.g., between 0 degrees and 25 degrees, between 0 degreesand 20 degrees, between 0 degrees and 15 degrees, between 0 degrees and10 degrees, etc.). Smaller angles (e.g., 0-15°) may be particularlybeneficial because the illumination (light source) and sensing(detector(s), e.g., camera(s), etc.) may be closer to each other, andmay provide a scanning wand for the intraoral scanner that can be moreeasily positioned and moved around a subject's teeth. These small-anglepenetration images and imaging techniques may also be referred to hereinas reflective illumination and/or imaging, or as reflective/scatteringimaging. In general penetrating imaging may refer to any appropriatetype of penetrating imaging unless otherwise specified, includingtrans-illumination, small-angle penetration imaging, etc. However, smallsmall angles may also result in direct reflection from the surface ofthe object (e.g., teeth), which may obscure internal structures.

The methods and apparatuses described here are particularly effective incombining a 3D surface model of the tooth or teeth with the imagedinternal features such as lesions (caries, cracks, etc.) that may bedetected by the use of penetration imaging by using an intraoral scannerthat is adapted for separate but concurrent (or nearly-concurrent)detection of both the surface and internal features. Combining surfacescanning and the penetration imaging may be performed by alternating orswitching between these different modalities in a manner that allows theuse of the same coordinate system for the two. Alternatively, bothsurface and penetrative scanning may be simultaneously viewed, forexample, by selectively filtering the wavelengths imaged to separate theIR (near-IR) light from the visible light. The 3D surface data maytherefore provide important reference and angle information for theinternal structures, and may allow the interpretation and analysis ofthe penetrating images that may otherwise be difficult or impossible tointerpret.

For example, described herein are methods for generating a model of asubject's teeth including the steps of: capturing three-dimensional (3D)surface model data of at least a portion of a subject's tooth using anintraoral scanner; taking a plurality of images into the tooth using apenetrative wavelength with the intraoral scanner; and forming a 3Dmodel of the tooth including internal structure using the 3D surfacemodel data and the plurality of images.

A method for generating a model of a subject's teeth may include:capturing three-dimensional (3D) surface model data of at least aportion of a subject's tooth with an intraoral scanner operating in afirst imaging modality, wherein the 3D surface model data has a firstcoordinate system; taking a plurality of images into the tooth with theintraoral scanner operating in a second imaging modality using apenetrative wavelength, wherein the plurality of images reference thefirst coordinate system; and forming a 3D model of the tooth includinginternal structures using the 3D surface model data and the plurality ofimages. In general, the capturing the first wavelength does notnecessarily capture images, but may directly capture a 3D surface scan.The second penetrating modalities may be captured as images processed asdescribed herein.

In general, capturing the 3D surface model data may include determininga 3D surface topology using any appropriate method. For example,determining a 3D surface topology may include using confocal focusing.Capturing the 3D surface model data may comprise using on or more of:confocal scanning, stereo vision or structured light triangulation.

Any of the methods and apparatuses described herein may be used tomodel, image and/or render a 3D image of a single tooth or region of atooth, multiple teeth, teeth and gums, or other intraoral structures,particularly from within a subject's mouth.

In general, the methods and apparatuses for performing them describedherein include 3D color intraoral scanning/scanners. For example, themethods may include capturing color intraoral 3D data.

As will be described in greater detail below, the method and apparatusesmay control the switching between collecting surface data and collectingpenetration imaging (penetrative) data. For example, any of thesemethods may include taking images using the penetrative wavelength asthe 3D surface model data is being captured, e.g., by switching betweenthe first imaging modality and the second (penetrative) imagingmodality.

The same sensor or a different sensor may be used to collect the surfaceand internal feature data. For example, taking the plurality of imagesmay comprise using a same sensor on the intraoral scanner to capture 3Dsurface model data and the plurality of images using the penetrativewavelength. Alternatively, a separate sensor or sensors may be used. Forexample, taking the plurality of images may comprise using a differentsensor on the intraoral scanner to capture 3D surface model data and theplurality of images using the penetrative wavelength.

As mentioned, taking images of the tooth using the penetrativewavelength (or penetrative spectral range) may include takingpenetration images at any angle between the illumination source and thesensor (e.g., detector or camera). In particular, internal feature(e.g., reflective imaging) data may be imaged using a small angleconfiguration, in which one or preferably more penetration images aretaken at different orientations relative to the tooth/teeth. Forexample, taking the plurality of images may comprise illuminating thetooth at an angle of between 0° and 15° relative to a sensor (e.g.,detector, camera, etc.) receiving the illumination from the tooth,reflecting off of the internal composition of the tooth/teeth. Takingthe plurality of images (e.g., penetration images such as thesesmall-angle penetration images) generally includes taking one or more(e.g., a plurality, including two or more, three or more, etc.)penetration images at different angles of the intraoral scanner relativeto the tooth over the same region of the tooth. Thus, the same internalregion of the tooth will appear in multiple different scans fromdifferent angles.

In general, any number of sensors may be included on the intraoralscanner, e.g., the wand of the intraoral scanner. Any appropriate sensorfor detecting and recording the appropriate spectral range(s) (e.g., oflight) may be used. Sensors may be referred to and may includedetectors, cameras, and the like. For example, taking a plurality ofimages may comprise using a plurality of sensors on the intraoralscanner to capture the plurality of images using the penetrativewavelength.

The illumination used to take a penetration image is generallypenetrative, so that it may at least partially penetrate and passthrough the enamel and dentin of the teeth. Penetrative wavelengths oflight may include generally infrared (and particularly near infrared)light. For example, light in the range of 700 to 1090 nm (e.g., 850 nm)may be used. Other wavelengths and ranges of wavelengths may be used,including wavelengths shorter than the visible spectrum. Thus, takingthe plurality of images may comprise illuminating the tooth withinfrared light. Taking the plurality of images (e.g., penetrationimages) may include illuminating the tooth with one or more of whitelight (including but not limited to white light trans-illumination),UV/Blue fluorescence and red light fluorescence.

The illumination used to take a penetration image can be consideredsemi-penetrative in the sense that internal tooth regions (e.g., pointsor voxels) may be visible from only a few camera positions andorientations; the point may be obstructed by other structures in someimages which include the volume point in their field of view. In thatsense, images that include the volume point in their field of view maynot image this volume point. Thus, the methods and apparatuses describedherein may take into account the high masking of volume points, unlikeother penetrative scanning techniques such as CT, which uses X-rayimaging in which no masking occurs.

In general, any appropriate technique may be used to form the 3D modelsof the tooth including the (combined) surface and internal structuresfrom the penetration imaging. These 3D models may be referred to ascombined 3D surface/volume models, 3D volumetric surface models, orsimply “3D models,” or the like. As mentioned, both the surface data andthe penetration imaging data may generally be in the same coordinatesystem. The two may be combined by using the common coordinate system.In some variations the surface data may be expressed as a surface modeland the internal features added to this model. In some variations thedata may be reconstructed into a three-dimensional model concurrently(after adding together). One or both datasets may be separately modified(e.g., filtered, subtracted, etc.). For example, forming the 3D model ofthe tooth including internal structures may comprise combing the 3Dsurface model data with an internal structure data (including volumetricdata). Forming the 3D model of the tooth including internal structuresmay comprise combining the plurality of penetration images, wherein theplurality of penetration images may be taken from different angles usingthe intraoral scanner.

In any of the methods and apparatuses configured to perform thesemethods described herein, the data may be analyzed automatically ormanually by the system. In particular, the method and apparatusesdescribed herein may include examining internal features and/oridentifying features of interest, including crack and caries. Featuresmay be recognized based on feature-recognition criterion (e.g., dark orlight regions in the penetration images), pattern-recognition, machinelearning, or the like. Features may be marked, including coloring,labeling or the like. Feature may be marked directly in the 3D model, onthe penetration image, or in a data structure that references (e.g.,shares a coordinate system with) the 3D model of the tooth formed by themethods and apparatuses described herein.

Also described herein are apparatuses configured to perform any of themethods described. For example, described herein are intraoral scanningsystems for generating a model of a subject's teeth that include: ahand-held wand having at least one sensor and a plurality of lightsources, wherein the light sources are configured to emit light at afirst spectral range and a second spectral range, wherein the secondspectral range is penetrative; and one or more processors operablyconnected to the hand-held wand, the one or more processors configuredto: generate a three-dimensional (3D) surface model of at least aportion of a subject's tooth using light from a first spectral range;and generate a 3D model of the subject's tooth including internalstructures based on the 3D surface model and on a plurality of imagestaken at the second spectral range showing internal structures.

An intraoral scanning system for generating a model of a subject's teethmay include: a hand-held wand having at least one sensor and a pluralityof light sources, wherein the light sources are configured to emit lightat a first spectral range and a second spectral range, further whereinthe second spectral range is penetrative; and one or more processorsoperably connected to the hand-held wand, the one or more processorsconfigured to: determine surface information by using light in the firstspectral range sensed by the hand-held wand, using a first coordinatesystem; generate a three-dimensional (3D) surface model of at least aportion of a subject's tooth using the surface information; take aplurality of images in the second spectral range, wherein the imagesreference the first coordinate system; and generate a 3D model of thesubject's tooth including internal structures based on the 3D surfacemodel and the a plurality of images.

Also described herein are methods of generating a model of a subject'steeth that include both surface and internal structures in which thesame intraoral scanner is cycled between different modalities such asbetween surface scanning and penetration; additional modalities (e.g.,laser florescence, etc.) may also alternatively be included. In general,although the examples described herein focus on the combination ofsurface and penetration, other internal scanning techniques (e.g., laserflorescence) may be used instead or in addition to the internal featureimaging described herein.

For example, described herein are methods of generating a model of asubject's teeth including both surface and internal structures includingthe steps of: using a hand-held intraoral scanner to scan a portion of asubject's tooth using a first modality to capture three-dimensional (3D)surface model data of the tooth; using the hand-held intraoral scannerto scan the portion of the subject's tooth using a second modality toimage into the tooth using a penetrative wavelength to capture internaldata of the tooth; cycling between the first modality and the secondmodality, wherein cycling rapidly switches between the first modalityand the second modality so that images using the penetrative wavelengthshare a coordinate system with the 3D surface model data captured in thefirst modality.

Any of the methods described herein may include automatically adjustingthe duration of time spent scanning in first modality, the duration oftime spent in the second modality, or the duration of time spent in thefirst and the second modality when cycling between the first modalityand the second modality. For example, any of these methods may includeautomatically adjusting a duration of time spent scanning in firstmodality, the duration of time spent in the second modality, or theduration of time spent in the first and the second modality when cyclingbetween the first modality and the second modality based on the captured3D surface model data, the internal data, or both the 3D surface modeldata and the internal data. Thus, a method of generating a model of asubject's teeth may include: using a hand-held intraoral scanner to scana portion of a subject's tooth using a first modality to capturethree-dimensional (3D) surface model data of the tooth; using thehand-held intraoral scanner to scan the portion of the subject's toothusing a second modality to image into the tooth using a penetrativewavelength to capture internal data of the tooth; cycling between thefirst modality and the second modality using a scanning scheme whereincycling rapidly switches between the first modality and the secondmodality so that the internal data uses the same coordinate system asthe 3D surface model data captured in the first modality; and adjustingthe scanning scheme based on the captured 3D surface model data, theinternal data, or both the 3D surface model data and the internal data.

The scanning scheme adjustment may comprise adjusting based ondetermination of the quality of the captured 3D surface model data.Adjusting the scanning scheme may comprise automatically adjusting thescanning scheme, and/or adjusting a duration of scanning in the firstmodality and/or adjusting a duration of scanning in the second modality.

Any of these methods may include combining the 3D surface model data andthe internal data of the tooth to form a 3D model of the tooth.

As mentioned above, capturing the 3D surface model data may includedetermining a 3D surface topology using confocal focusing/confocalscanning, stereo vision or structured light triangulation.

In general, cycling may comprise cycling between the first modality, thesecond modality, and a third modality, wherein cycling rapidly switchesbetween the first modality, the second modality and the third modalityso that images using the penetrative wavelength share a coordinatesystem with the 3D surface model captured in the first modality. Thethird modality may be another penetrative modality or a non-penetrativemodality (e.g., color, a visual image the subject's tooth, etc.).

Using the hand-held intraoral scanner to scan the portion of thesubject's tooth using the second modality may include illuminating thetooth at an angle of between 0° and 15° relative to a direction of viewof the sensor receiving the illumination (e.g., small angleillumination). The step of using the hand-held intraoral scanner to scanthe portion of the subject's tooth using the second modality may includetaking a plurality of penetration images at a plurality of differentangles between an illumination source and a sensor and/or at a pluralityof different positions or angles relative to the tooth so that the sameinternal region of the tooth is imaged from different angles relative tothe tooth.

As mentioned, any appropriate penetrative wavelength may be used,including infrared (e.g., near infrared). For example using thehand-held intraoral scanner to scan the portion of the subject's toothusing the second modality may comprise illuminating with one or more of:white light trans-illumination, UV/Blue fluorescence, and red lightfluorescence.

Also described herein are intraoral scanning systems for generating amodel of a subject's teeth that are configured to cycle between scanningmodes. For example, described herein are intraoral scanning systemscomprising: a hand-held intraoral wand having at least one sensor and aplurality of light sources, wherein the light sources are configured toemit light at a first spectral range and at a second spectral range,further wherein the second spectral range is penetrative; and one ormore processors operably connected to the hand-held intraoral wand, theone or more processors configured to cause the wand to cycle between afirst mode and a second mode, wherein in the first mode the wand emitslight at the first spectral range for a first duration and the one ormore processors receives three dimensional (3D) surface data inresponse, and wherein in the second mode the wand emits light at thesecond spectral range for a second duration and the one or moreprocessors receives image data in response.

An intraoral scanning system for generating a model of a subject's teethmay include: a hand-held intraoral wand having at least one sensor and aplurality of light sources, wherein the light sources are configured toemit light at a first spectral range and at a second spectral range,further wherein the second spectral range is penetrative; and one ormore processors operably connected to the wand, the one or moreprocessors configured to cause the wand to cycle between a first modeand a second mode, wherein in the first mode the wand emits light at thefirst spectral range for a first duration and the one or more processorsreceives three dimensional (3D) surface data in response, and wherein inthe second mode the wand emits light at the second spectral range for asecond duration and the one or more processors receives image data inresponse; wherein the one or more processors is configured to adjustingthe first duration and the second duration based on the received 3Dsurface data, the received image data, or both the 3D surface data andthe image data. In any of the apparatuses described herein, one mode maybe the surface scanning (3D surface), which may be, for example, at 680nm. Another mode may be a penetrative scan, using, e.g., near-IR light(e.g., 850 nm). Another mode may be color imaging, using white light(e.g., approximately 400 to 600 nm).

Penetration imaging methods for visualizing internal structures using ahand-held intraoral scanner are also described. Thus, any of the generalmethods and apparatuses described herein may be configured specificallyfor using penetration imaging data to model a tooth or teeth to detectinternal features such as crack and caries. For example, a method ofimaging through a tooth to detect cracks and caries may include: takinga plurality of penetration images through the tooth at differentorientations using a hand-held intraoral scanner in a first position,wherein the intraoral scanner is emitting light at a penetrativewavelength; determining surface location information using the intraoralscanner at the first position; and generating a three-dimensional (3D)model of the tooth using the plurality of penetration images and thesurface location information.

Generating a 3D model of the tooth may comprise repeating the steps oftaking the plurality of penetration images and generating the 3D modelfor a plurality of different locations.

Taking the plurality of penetration images through the tooth atdifferent orientations may include taking penetration images in whicheach penetration image is taken using either or both of: a differentillumination source or combination of illumination sources on theintraoral scanner emitting the penetrative wavelength or a differentimage sensor on the intraoral scanner taking the image.

In some variations taking the plurality of penetration images maycomprise taking three or more penetration images.

Taking the plurality of penetration images through the tooth surface atdifferent orientations may comprises taking penetration images usingsmall angle illumination/viewing, for example, wherein, for eachpenetration image, an angle between emitted light and light received byan image sensor is between 0 and 15 degrees. For example, a method ofimaging through a tooth to detect cracks and caries may include:scanning a tooth from multiple positions, wherein scanning comprisesrepeating, for each position: taking a plurality of penetration imagesthrough the tooth at different orientations using an intraoral scanner,wherein the intraoral scanner is emitting light at a penetrativewavelength and wherein, for each penetration image, an angle betweenemitted light and light received by an image sensor is between 0 and 15degrees, and determining surface location information using theintraoral scanner; and generating a three-dimensional (3D) model of thetooth using the penetration images and the surface location information.

As mentioned above, in addition to the apparatuses (e.g., scanningapparatuses, tooth modeling apparatuses, etc.) and methods of scanning,modeling and operating a scanning and/or modeling apparatus, alsodescribed herein are methods of reconstructing volumetric structuresusing images generated from one or more penetrative wavelengths.

For example, described herein are methods of reconstructing a volumetricstructure from an object including semi-transparent strongly scatteringregions (e.g., a tooth) for a range of radiation wavelengths. The methodmay include illuminating the object with a light source that is emitting(e.g., exclusively or primarily radiating) a penetrating wavelength,taking a plurality of images of the object with a camera sensitive tothe penetrating wavelength (e.g., recording in the range of radiationwavelengths), receiving location data representing a location of thecamera relative to the object for each of the plurality of images,generating for each point in a volume an upper bound on a scatteringcoefficient from the plurality of images and the location data, andgenerating an image of the object from the upper bound of scatteringcoefficients for each point. The penetrating wavelength of light appliedto the object may be emitted from substantially the same direction asthe camera. The image or images generated may illustrate features withinthe volume of the object, and the image may also include (or be modifiedto include) the outer boundary of the object, as well as the internalstructure(s).

As used herein, a tooth may be described as an object includingsemi-transparent strongly scattering region or regions; in general,teeth may also include strong scattering regions (such as dentine), andlightly scattering, highly transparent regions (such as the enamel) atnear-IR wavelengths. Teeth may also include regions having intermedia ormixed scattering properties, such as caries. The methods and apparatusesfor performing volumetric scans described herein are well suited formapping these different regions in the tooth/teeth.

A method of reconstructing a volumetric structure from an objectincluding semi-transparent strongly scattering regions for a range ofradiation wavelengths may include: taking a plurality of images of theobject with a camera in the range of radiation wavelengths, whereinlighting for the plurality of images is projected substantially from adirection of the camera, receiving location data representing a locationof the camera relative to the object for each of the plurality ofimages, generating for each point in a volume an upper bound on ascattering coefficient from the plurality of images and the locationdata, and generating an image of the object from the upper bound ofscattering coefficients for each point.

The range of radiation wavelengths may be infrared or near infraredwavelength(s).

Any of these methods may also include receiving surface datarepresenting an exterior surface of the object, wherein the generatingstep is performed for each point in the volume within the exteriorsurface of the object.

The object may comprise a tooth, having an exterior enamel surface andan interior dentin surface. Teeth are just one type of object includingsemi-transparent strongly scattering regions; other examples may includeother both tissues (including soft and/or hard tissues), e.g., bone,etc. These objects including semi-transparent strongly scatteringregions may include regions that are typically semi-transparent andstrongly scattering for the penetrative wavelengths (e.g., the infraredor near infrared wavelengths), as described herein.

The location data may generally include position and orientation data ofthe camera at the time of capturing each of the plurality of images. Forexample, the location data may comprise three numerical coordinates in athree-dimensional space, and pitch, yaw, and roll of the camera.

Generating for each point in the volume the upper bound on scatteringcoefficients may comprise projecting each point of a 3D grid of pointscorresponding to the volume of the object onto each of the pluralityimages using a first calibration, producing a list of intensity valuesfor each projected point, converting each intensity value on the list ofintensity values to a scattering coefficient according to a volumeresponse, and storing a minimum scattering coefficient value for eachgrid point from the list of scattering coefficient values.

For example, the first calibration may comprise a fixed pattern noisecalibration to calibrate for sensor issues and image ghosts of thecamera. The first calibration may comprise a camera calibration thatdetermines a transformation for the camera that projects known points inspace to points on an image.

Also described herein are methods of reconstructing a volumetricstructure from a tooth, semi-transparent in a range of radiationwavelengths, the method comprising receiving, in a processor, arepresentation of a surface of the tooth in a first coordinate system,receiving, in the processor, a plurality of images of the tooth in therange of radiation wavelengths, the plurality of images taken withlighting projected substantially from a direction of a camera,receiving, in the processor, location data representing a location ofthe camera for each of the plurality of images, projecting each point ofa grid of points corresponding to a volume within the surface of thetooth onto each of the plurality images using a first calibration,producing a list of intensity values for each projected point,converting each intensity value on the list of intensity values to ascattering coefficient according to a volume response, and storing aminimum scattering coefficient for each point into a list of minimumscattering coefficients.

Any of these methods may further comprise producing an image from thelist of minimum scattering coefficients.

The location data may comprise position and orientation data of thecamera (or cameras) at the time of capturing each of the plurality ofimages.

The first calibration may comprise a fixed pattern noise calibration tocalibrate for sensor issues and image ghosts of the camera. In someembodiments, the first calibration may comprise a camera calibrationthat determines a transformation for the camera that projects knownpoints in space to points on an image.

The method may further comprise receiving surface data representing anexterior surface of the object, wherein the projecting step is performedfor each point inside the volume within the exterior surface of theobject.

The grid of points may comprise a cubic grid.

Any of the methods described herein may be embodied as software,firmware and/or hardware. For example, any of these methods may beconfigured as non-transitory computing device readable medium havinginstructions stored thereon for performing the method.

For example, a non-transitory computing device readable medium havinginstructions stored thereon for reconstructing a volumetric structurefrom a tooth that is semi-transparent in a range of radiationwavelengths is described. The instructions may be executable by aprocessor to cause a computing device to receive a representation of asurface of the tooth in a first coordinate system, receive a pluralityof images of the tooth in the range of radiation wavelengths, theplurality of images taken with lighting projected substantially from adirection of a camera, receive location data representing a location ofthe camera for each of the plurality of images, project each point of agrid of points corresponding to a volume of the tooth onto each of theplurality of images using a first calibration, produce a list ofintensity values for each projected point, convert each intensity valueon the list of intensity values to a scattering coefficient according toa volume response, and store a minimum scattering coefficient for eachpoint into a list of minimum scattering coefficients, and produce animage from the list of minimum scattering coefficients.

The location data may comprise position and orientation data of thecamera at the time of capturing each of the plurality of near-infraredimages. The location data may comprise three numerical coordinates in athree-dimensional space, and pitch, yaw, and roll of the camera.

The first calibration may comprise a fixed pattern noise calibration tocalibrate for sensor issues and image ghosts of the camera. The firstcalibration may comprise a camera calibration that determines atransformation for the camera that projects known points in space topoints on an image.

The grid of points may be inside the tooth; as mentioned, the grid ofpoints may comprise a cubic grid.

Alternatively or additionally to the use of scattering coefficients, anyappropriate method of forming the internal structures of the patient'steeth using the penetrative wavelength images. For example, any of theapparatuses (e.g., systems, devices, software, etc.) and methodsdescribed herein may use the two-dimensional penetrative images alongwith position and/or orientation information about the scanner relativeto the object being imaged (e.g., the teeth) to segment the 2Dpenetrative images to form a three-dimensional model of the teethincluding an internal structure from within the teeth. As described, apenetrative image may refer to an images taken with a near-IR and/or IRwavelength), penetrating into the object. The position and/ororientation of the scanner may be a proxy for the position and/ororientation of the camera taking the images which is one the scanner(e.g., on a handheld wand).

For example, described herein are methods of modeling a subject's teeth,comprising: capturing, with an intraoral scanner, a plurality of imagesof an interior of the subject's teeth and a position and orientation ofthe intraoral scanner specific to each image of the plurality of images;segmenting the plurality of images to form an internal structurecorresponding to a structure within the subject's teeth; using theposition and orientation of the plurality of images to project theinternal structure onto a three-dimensional model of the subject'steeth; and displaying the three-dimensional model of the subject's teethincluding the internal structure.

In any of these methods and apparatuses, the 3D surface model may beconcurrently captured using a non-penetrative wavelength (e.g., surfacescan) while capturing the penetrative images. For example, capturing maycomprise capturing surface images of the subject's teeth while capturingthe plurality of images of the interior of the subject's teeth. Themethod may also include forming the three dimensional model of thesubject's teeth from the captured surface images. For example, formingthe three dimensional model of the subject's teeth may comprisedetermining a three-dimensional surface topology using confocalfocusing. Capturing the surface images of the subject's teeth maycomprise using confocal scanning, stereo vision or structured lighttriangulation.

In general, the same device (e.g., scanner) may model and/or display the3D representation of the teeth, including the internal structures,alternatively or additionally a separate processor (e.g., remote to thescanner) may be used. Any of these methods may also include storingand/or transmitting plurality of penetrative images and the position andorientation of the intraoral scanner while capturing the plurality oftwo-dimensional images, including transmitting to a remote processor forperforming the segmentation and later steps.

In any of the methods and apparatuses described herein, the 3D modelincluding the internal structure(s) may be displayed while the scanneris operating. This may advantageously allow the user to see, inreal-time or near real-time the internal structure(s) in the subject'steeth. Thus, any of these methods may include displaying thethree-dimensional model as the images are captured.

Segmenting the plurality of images may comprise applying edge detectionto the plurality of images to identify closed boundaries within theplurality of images. Segmenting the plurality of images may compriseforming a volumetric density map from the plurality of images toidentify the internal structure. Segmenting the volumetric density mapmay include segmenting by identifying one or more iso-surfaces withinthe volumetric density map to identify the internal features. Any ofthese methods may include segmenting the volumetric density map toidentify the internal feature (e.g., cracks, caries, dental fillings,dentin, etc.).

For example, an intraoral scanning apparatus configured to generate amodel of a subject's teeth may include: an intraoral scanner having aplurality of light sources and a position and orientation sensor,wherein the light sources are configured to emit light at a firstspectral range and at a second spectral range, further wherein thesecond spectral range is penetrative; and a processor operably connectedto the intraoral scanner, the one or more processors configured to causethe scanner to capture a plurality of images and position andorientation of the intraoral scanner corresponding to each of theplurality of images when the intraoral scanner is emitting light at thesecond spectral range; wherein the processor is further configured tosegment the plurality of images to form an internal structurescorresponding to a structure within the subject's teeth, and to displayor transmit a three-dimensional model of the subject's teeth includingthe internal structure.

The processors may be configured to segment the plurality of images byapplying edge detection to the plurality of images to identify closedboundaries within the plurality of images. The processor may beconfigured to segment the plurality of images by forming a pixel densitymap from the plurality of images to identify the internal structure. Theprocessor may be configured to identify closed segments within the pixeldensity map to identify the internal structure.

Also described herein are non-transitory computing device readablemedium having instructions stored thereon that are executable by aprocessor to cause an intraoral scanning apparatus to: capture aplurality of images using a penetrative wavelength of light and aposition and orientation of the intraoral scanner specific to each imageof the plurality of images; segment the plurality of images to form aninternal structure corresponding to a structure within a subject'steeth; use the position and orientation of the intraoral scannerspecific to each image to project the internal structure onto athree-dimensional model of the subject's teeth; and display thethree-dimensional model of the subject's teeth including the internalstructure.

The non-transitory computing device readable medium having instructionsmay be further configured to cause the intraoral scanning apparatus tosegment the plurality of images by applying edge detection to theplurality of images to identify closed boundaries within the pluralityof images. The non-transitory computing device readable medium havinginstructions may be further configured to cause the intraoral scanningapparatus to segment the plurality of images by forming a pixel densitymap from the plurality of images to form the internal structure. Thenon-transitory computing device readable medium having instructions maybe further configured to cause the intraoral scanning apparatus tosegment the plurality of images by identifying closed segments withinthe pixel density map to form the internal structure.

Also described herein are non-transitory computing device readablemedium having instructions stored thereon that are executable by aprocessor to cause a computing device to: receive, from a scanner,three-dimensional surface model data of a subject's teeth; receive, fromthe scanner, a plurality of images of an interior of the subject's teethand position and orientation of the intraoral scanner specific to eachimage of the plurality of images; segment the plurality of images toform an internal structure of the subject's teeth; project the internalstructure of the subject's teeth onto the three-dimensional surfacemodel; and display the three-dimensional surface model showing theinternal structure.

For example, described herein are methods for generating athree-dimensional (3D) volumetric model of a subject's teeth using anintraoral scanner, the method comprising: capturing 3D surface modeldata of at least a portion of the subject's teeth using an intraoralscanner as the intraoral scanner is moved over the teeth; taking aplurality of images into the teeth using a near-infrared (near-IR)wavelength with the intraoral scanner as the intraoral scanner is movedover the teeth so that multiple images of a same internal region of theteeth are imaged; determining, for each of the plurality of images intothe teeth, a position of the intraoral scanner relative to the subject'steeth using the 3D surface model data; and forming the 3D volumetricmodel of the subject's teeth including internal features using theplurality of images and the position of the intraoral scanner relativeto the subject's teeth.

A method for generating a three-dimensional (3D) volumetric model of asubject's teeth using an intraoral scanner may include: capturing 3Dsurface model data of at least a portion of the subject's teeth using anintraoral scanner as the intraoral scanner is moved over the teeth;taking a plurality of images into the teeth using a near-infrared(near-IR) wavelength as the intraoral scanner is moved over the teeth byemitting a near-IR light from the intraoral scanner in a firstpolarization, and detecting, in an image sensor in the intraoralscanner, the near-IR light returning to the intraoral scanner, whereinthe near-IR light returning to the intraoral scanner is filtered toremove specular reflection by filtering near-IR light in the firstpolarization from the near-IR light returning to the intraoral scannerbefore it reaches the image sensor; determining, for each of theplurality of images into the teeth, a position of the intraoral scannerrelative to the subject's teeth when each of the plurality of images iscaptured, using the 3D surface model data; and forming the 3D volumetricmodel of the subject's teeth including internal features using theplurality of images and the position of the intraoral scanner relativeto the subject's teeth.

In any of these methods and apparatuses, the near-IR light returning tothe intraoral scanner may be filtered to remove specular reflection byfiltering all or nearly all of the near-IR light in the firstpolarization from the near-IR light returning to the intraoral scannerbefore it reaches the image sensor.

Also described herein are intraoral scanners scan both surface andinternal structures. For example, an intraoral scanning system forgenerating a three-dimensional (3D) volumetric model of a subject'steeth may include: a hand-held wand having at least one image sensor anda plurality of light sources, wherein the light sources are configuredto emit light at a first spectral range and a second spectral range,wherein the second spectral range is within near-infrared (near-IR)range of wavelengths; and one or more processors operably connected tothe hand-held wand, the one or more processors configured to: capture 3Dsurface model data of at least a portion of the subject's teeth as theintraoral scanner is moved over the teeth; take a plurality of imagesinto the teeth using light in the second spectral range as the intraoralscanner is moved over the teeth so that multiple images of a sameinternal region of the teeth are imaged; determine, for each of theplurality of images into the teeth, a position of the hand-held wandrelative to the subject's teeth using the 3D surface model data; andform the 3D volumetric model of the subject's teeth including internalfeatures using the plurality of images and the position of the intraoralscanner relative to the subject's teeth.

An intraoral scanning system for generating a three-dimensional (3D)volumetric model of a subject's teeth may include: a hand-held wandhaving at least one image sensor and a plurality of light sources,wherein the light sources are configured to emit light at a firstspectral range and a second spectral range, wherein the second spectralrange is within near-infrared (near-IR) range of wavelengths; a filterin front of the image sensor configured to filter light in the secondspectral range and the first polarization; and one or more processorsoperably connected to the hand-held wand, the one or more processorsconfigured to: capture 3D surface model data of at least a portion ofthe subject's teeth as the intraoral scanner is moved over the teeth;take a plurality of images into the teeth using light in the secondspectral as the intraoral scanner is moved over the teeth by emitting anear-IR light from the intraoral scanner in a first polarization, anddetecting, in an image sensor in the intraoral scanner, the near-IRlight returning to the intraoral scanner, wherein the near-IR lightreturning to the intraoral scanner is filtered to remove specularreflection by filtering near-IR light in the first polarization from thenear-IR light returning to the intraoral scanner before it reaches theimage sensor; determine, for each of the plurality of images into theteeth, a position of the hand-held wand relative to the subject's teethusing the 3D surface model data; and form the 3D volumetric model of thesubject's teeth including internal features using the plurality ofimages and the position of the intraoral scanner relative to thesubject's teeth.

Also described herein are methods of imaging cracks and caries in teeth.For example, described herein are methods of imaging into a subject'steeth to detect cracks and caries using an intraoral scanner, the methodcomprising: scanning the intraoral scanner over the subject's teeth;taking a plurality of near-infrared (near-IR) images into the subject'steeth at different orientations using the intraoral scanner emittingboth a near-IR wavelength and a non-penetrative wavelength; determininga position of the intraoral scanner relative to the subject's teeth foreach location of an image from the plurality of near-IR images using thenon-penetrative wavelength; and generating a three-dimensional (3D)volumetric model of the subject's teeth using the plurality of near-IRimages and the position of the intraoral scanner relative to thesubject's teeth for each near-IR image of the plurality of near-IRimages.

Any of these methods may include analyzing the volumetric model toidentify a crack or caries (or other internal regions of the teeth).

For example, a method of imaging through a subject's teeth to detectcracks and caries may include: scanning the subject's teeth frommultiple positions, wherein scanning comprises repeating, for eachposition: taking a plurality of near-infrared (near-IR) images into theteeth at different orientations using an intraoral scanner, wherein theintraoral scanner is emitting light at a near-IR wavelength in a firstpolarization and wherein, for each near-IR image, an angle betweenemitted light and light received by an image sensor is between 0 and 15degrees, further wherein received near-IR light is filtered to blocknear-IR light in the first polarization, and determining a position ofthe intraoral scanner relative to the subject's teeth for each locationof an image from the plurality of near-IR images using; and generating athree-dimensional (3D) volumetric model of the tooth using thepenetration images and the surface location information.

Also described herein are methods of using scattering coefficients togenerate internal images of tooth based on penetrating images and camerasensor location. For example, a method of forming a three-dimensional(3D) volumetric model of a subject's teeth may include: taking aplurality of near-infrared (near-IR) images of the subject's teeth witha camera sensor, wherein the near-IR lighting for the plurality ofnear-IR images is projected substantially from a direction of the camerasensor; receiving location data representing a location of the camerarelative to the subject's teeth for each of the plurality of near-IRimages; generating, for each point in a volume, an upper bound on ascattering coefficient from the plurality of near-IR images and thelocation data; combining the upper bound of scattering coefficients foreach point in a volume to form a 3D volumetric model of the subject'steeth; and outputting the 3D volumetric model of the subject's teeth.

Any of these methods may include forming an iso-surface from the 3Dvolumetric model of the subject's teeth. The iso-surface may be formedby selecting a threshold or range of values of the scatteringcoefficients. Sub-ranges may correspond to different internal regions(e.g., structures). For example, outputting may comprise forming aniso-surface corresponding to an interior dentin surface from the 3Dvolumetric model of the subject's teeth.

A method of reconstructing a volumetric structure from a tooth, whereinthe tooth is semi-transparent in a range of radiation wavelengths, mayinclude: receiving, in a processor, a representation of a surface of thetooth in a first coordinate system; receiving, in the processor, aplurality of images of the tooth taken by a camera in the range ofradiation wavelengths, the plurality of images taken with lightingprojected substantially from a direction of the camera; receiving, inthe processor, location data representing a location of the camera foreach of the plurality of images; projecting each point of a grid ofpoints corresponding to a volume within the surface of the tooth ontoeach of the plurality images using a first calibration; producing a listof intensity values for each projected point; converting each intensityvalue on the list of intensity values to a scattering coefficientaccording to a volume response; and storing a minimum scatteringcoefficient for each point into a list of minimum scatteringcoefficients.

Any of these methods may be embodied in an apparatus, includingsoftware, hardware and/or firmware for performing the method. Forexample, described herein are non-transitory computing device readablemedium having instructions stored thereon for reconstructing avolumetric structure from a tooth that is semi-transparent in a range ofradiation wavelengths, wherein the instructions are executable by aprocessor to cause a computing device to: receive a representation of asurface of the tooth in a first coordinate system; receive a pluralityof images of the tooth taken by a camera in the range of radiationwavelengths, the plurality of images taken with lighting projectedsubstantially from a direction of the camera; receive location datarepresenting a location of the camera for each of the plurality ofimages; project each point of a grid of points corresponding to a volumeof the tooth onto each of the plurality of images using a firstcalibration; produce a list of intensity values for each projectedpoint; convert each intensity value on the list of intensity values to ascattering coefficient according to a volume response; and store aminimum scattering coefficient for each point from the scatteringcoefficients; and output an image produced from the list of minimumscattering coefficients.

Also described herein are methods of forming the internal structuresusing segmentation. For example, a method of modeling a subject's teeth,may include: capturing, with an intraoral scanner, a plurality of imagesof an interior of the subject's teeth and a position and orientation ofthe intraoral scanner specific to each image of the plurality of images;segmenting the plurality of images to form an internal structurecorresponding to a structure within the subject's teeth; using theposition and orientation of the plurality of images to project theinternal structure onto a three-dimensional model of the subject'steeth; and displaying the three-dimensional model of the subject's teethincluding the internal structure.

Also described herein are intraoral scanning apparatus configured togenerate a model of a subject's teeth, the apparatus comprising: anintraoral scanner having a plurality of light sources and a position andorientation sensor, wherein the light sources are configured to emitlight at a first spectral range and at a second spectral range, furtherwherein the second spectral range is penetrative; and a processoroperably connected to the intraoral scanner, the one or more processorsconfigured to cause the scanner to capture a plurality of images andposition and orientation of the intraoral scanner corresponding to eachof the plurality of images when the intraoral scanner is emitting lightat the second spectral range; wherein the processor is furtherconfigured to segment the plurality of images to form an internalstructures corresponding to a structure within the subject's teeth, andto display or transmit a three-dimensional model of the subject's teethincluding the internal structure.

Also described herein are non-transitory computing device readablemedium having instructions stored thereon that are executable by aprocessor to cause an intraoral scanning apparatus to: capture aplurality of images using a penetrative wavelength of light and aposition and orientation of the intraoral scanner specific to each imageof the plurality of images; segment the plurality of images to form aninternal structure corresponding to a structure within a subject'steeth; use the position and orientation of the intraoral scannerspecific to each image to project the internal structure onto athree-dimensional model of the subject's teeth; and display thethree-dimensional model of the subject's teeth including the internalstructure.

Also described herein are methods for forming 3D volumes (includingvolumetric volumes) of teeth. For example, described herein are methodscomprising: receiving data associated with an intraoral scan of asubject; determining, from the received data, at least a portion of avolume of a first internal feature of a tooth of the subject;determining, from the received data, at least a portion of a volume of asecond internal feature of the tooth of the subject, the first internalfeature differing from the second internal feature; mapping the portionof the volume of the first internal feature with the portion of thevolume of the second internal feature; outputting a 3D volume of theportion of the volume of the first internal feature with the portion ofthe volume of the second internal feature.

The received data may comprise data from tooth surface penetratingintraoral scan of the subject. The received data may further comprisedata from a tooth surface intraoral scan of the subject.

The method may also include determining, from the received data, asurface of the tooth of the subject; mapping the surface of the toothwith the portion of the volume of the first internal feature and theportion of the volume of the second internal feature; and outputting the3D volume with the surface of the tooth with the portion of the volumeof the first internal feature and the portion of the volume of thesecond internal feature.

The received data may further comprise data from a tooth surface colorintraoral scan of the subject.

The method may also comprise, determining, from the received data, acolor of the surface of the tooth of the subject; mapping the color ofthe surface of the tooth to the surface of the tooth; and outputting the3D volume with the surface of the tooth and the color of the surface ofthe tooth.

The first internal feature of the tooth may comprise a dentin of thetooth and the second internal feature of the tooth comprises an enamelof the tooth. The intraoral scan may comprise a second intraoral scan ofthe subject; and wherein the method further comprises receiving dataassociated with a prior intraoral scan of the subject; determining fromthe received data associated with the prior intraoral scan of thesubject, at least a portion of a volume of the enamel or the dentin; anddetermining a volume change of the enamel or the dentin by comparing theportion of the volume of the enamel or the dentin determined from thereceived data associated with the second intraoral scan and the portionof the volume of the enamel or the dentin determined from the receiveddata associated with the prior intraoral scan; and outputting thedetermined volume change.

The method may also include detecting a dental caries of the tooth bycomparing the second internal feature and the first internal feature andoutputting a signal to the user associated with the detected dentalcaries. Comparing the second internal feature and the second internalfeature may comprise analyzing whether the volume of the second internalfeature extends from a surface of the volume of the first internalfeature. Analyzing may comprise determining whether the volume of thesecond internal feature extends from the surface of the volume of thefirst internal feature and to a portion of the second internal featureassociated with the dentin.

The method may also include calculating a volume of the second internalfeature that extends from the surface of the volume of the firstinternal feature and outputting a signal associated with the calculatedvolume.

Also described are method comprising: receiving data associated with anintraoral scan of a subject; determining, from the received data, avolume of a dental caries of a tooth of the subject; quantifying thevolume of the dental caries of the tooth of the subject; and outputtinga signal associated with the quantified volume of the dental caries ofthe tooth of the subject.

The method may also include determining, from the received data, avolume of an enamel of the tooth of the subject; mapping the volume ofthe enamel to the volume of the dental caries; and outputting a 3Dvolume of the mapped volumes of the enamel and the dental caries to auser. For example, determining, from the received data, a volume of adentin of the tooth of the subject; mapping the volume of the dentin tothe volume of the enamel and the volume of the dental caries; andoutputting the 3D volume of the mapped volumes of the enamel and thedental caries with the volume of the dentin.

The intraoral scan of the subject may comprise a second intraoral scanof the subject and wherein the method further comprises receiving dataassociated with a prior intraoral scan of the subject; determining, fromthe received data associated with the prior intraoral scan of thesubject, a prior volume of the dental caries of the tooth of thesubject; outputting a signal associated with a difference in volumebetween the volume of the dental caries and the prior volume of thedental caries. The method may also comprise outputting a 3D model of thevolume of the dental caries of the tooth of the subject.

Also described herein are trans-illumination adapter sleeve device foran intraoral scanner, the device comprising: a sleeve body configured tofit over a wand of an intraoral scanner, the sleeve body comprising alight-passing region at a distal end of the sleeve body configured toallow near-infrared (near-IR) light to pass through the sleeve; a firstwing region extending from the distal end of the sleeve body adjacent tothe light-passing region; and a near-IR light source configured to emitnear-IR light from the first wing region. The near-IR light source maybe configured to emit near-IR light transverse to the light-passingregion.

The device may also include a second wing region extending from thedistal end of the sleeve body adjacent to the light-passing regionhaving a second near-IR light source configured to emit near-IR lightfrom the second wing region. The device may also include an electricalcontact on a proximal end of the sleeve body configured to applyelectrical energy to the near-IR light source. The device may alsoinclude a flexible circuit coupling the electrical contact to thenear-IR light source. Any of these devices may include a camera sensoroperably connected to a second wing extending from the distal end of thesleeve body adjacent to the light-passing region.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe claims that follow. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1A illustrates one example of a 3D (color) intraoral scanner thatmay be adapted for used as described herein to generate a model ofsubject's teeth having both surface and internal features.

FIG. 1B schematically illustrates an example of an intraoral scannerconfigured to generate a model of subject's teeth having both surfaceand internal features.

FIG. 2A illustrates trans-illumination imaging through a tooth at 180°.

FIG. 2B illustrates trans-illumination imaging through a tooth at 90°.

FIGS. 2C and 2D show side and top perspective views, respectively, of anexample of a distal end of a wand of an intraoral scanner configured toprovide trans-illumination imaging through a tooth at 90° and 180°.

FIG. 2E shows a schematic of an intraoral scanner configured to do bothsurface scanning (e.g., visible light, non-penetrative) and penetrativescanning using a near infra-red (IR) wavelength. The scanner includes apolarizer and filters to block near-IR light reflected off the surfaceof the tooth while still collecting near-IR light reflected frominternal structures.

FIGS. 3A, 3B and 3C illustrate exemplary penetration with small angleillumination imaging orientations using an intraoral scanner wand suchas the one shown in FIGS. 2C and 2D.

FIG. 3D shows another example (similar to what is shown in FIG. 3A) ofilluminating with light (e.g., near-IR) on the right side and imagingfrom the left side (this orientation may be flipped) to get 180°trans-illumination. Higher and lower scattering is shown by the arrows.

FIG. 4A illustrates an example of a penetration imaging (e.g.,small-angle penetration imaging) configuration of sensors and light(illumination) sources in which the viewing vector between the sensorsand light sources is between 0° and 15° at different positions around atooth; these different positions represent different positions taken atdifferent times, e.g., by moving the wand/scanner around the tooth sothat penetrative images may be taken at different angles relative to thetooth.

FIGS. 4B-4F illustrate other variations of penetrative imaging similarto that shown in FIG. 4A, for imaging from a tooth. FIG. 4B shows anexample of a multi-camera, multi-light source scanner. FIGS. 4C-4F showalternative small-angle configurations.

FIGS. 5A-5I illustrate nine alternative penetration imaging orientationsthat may be used as part of an intraoral scanner such as the ones shownin FIGS. 1A-1B. In FIGS. 5A-5C the central sensor is active, and eitherthe right (FIG. 5B) or the left (FIG. 5A) or both (FIG. 5C) lightsources are illuminating the tooth. Similarly, in FIGS. 5D-5E the rightsensor is active, while in FIGS. 5G-5I the left sensor is active.

FIG. 6 is a diagram schematically illustrating one method of generatinga model of a subject's tooth or teeth having both surface and internalfeatures.

FIG. 7 is a diagram illustrating one variation of a method of generatinga model of a subject's teeth when having both surface and internalfeatures by cycling between different scanning modalities (e.g., surfacescanning, penetration imaging, etc.).

FIG. 8 is a graphical example of one a timing diagram for scanning asample (e.g., tooth) to generate a model having both surface andinternal features cycling between different scanning modalities (showingsurface scanning, laser florescence, viewfinder and penetration imagingmodalities). In FIG. 8, the y-axis indicates the lens position of the 3Dconfocal scanner (scan amplitude). The durations of each of the scans(e.g., the scanning time for each mode) may be fixed, it it may beadjustable. For example the duration of the penetrative scan (d) may bedynamically adjusted (e.g., increased or decreased) during scanning baseon the quality of the images received, the completeness of the 3Dreconstruction of internal structures, etc. Similarly, the duration ofthe surface scan may be dynamically adjusted during scanning based onthe quality of the image(s) being scanned (e.g., the prior images and/orthe current image, etc.), the completeness of the 3D surface model forthe region being scanned, etc.

FIG. 9A illustrates one example of an overlay of the penetration imagesin on a 3D surface model of the teeth, showing the image penetrationpanorama (in which penetrating images are stitched together to form thepanorama)

FIG. 9B illustrates the portion of the model reconstruction of FIG. 9Aincluding the surface and internal features. Note that in FIGS. 9A and9B, the overlay showing the internal structures is not a volumetricreconstruction.

FIG. 10A shows an example of a front view of one example of an intraoralscanner front end.

FIG. 10B shows an example of a bottom view of the intraoral scanner,showing the plurality of sensors and light sources.

FIGS. 11A-11C shows projected images looking down through the top of thetooth using a penetrative wavelength (e.g., near-IR).

FIGS. 11D-11F illustrate the movement of the light source relative tothe tooth in the z direction, using a penetrative wavelength.

FIGS. 11G-11I show the position of the scanner, such as thoseillustrated above, scanning the tooth in the z-direction. Note thatFIGS. 11A, 11D and 11G correspond to a first depth position, FIGS. 11B,11E and 11H correspond to a second (higher up the tooth) depth position,and FIGS. 11C, 11F and 11I correspond to a third (even higher up) depth.

FIG. 12 illustrates an example of a configuration of penetration lightsources (e.g., penetrative spectral range light) and cameras that may beused as part of an intraoral scanner wand.

FIG. 13 shows a flowchart that describes one method for reconstructing avolumetric structure from an object including semi-transparent stronglyscattering regions for a range of radiation wavelengths.

FIG. 14 illustrates another flowchart that provides method steps forreconstructing a volumetric structure from a tooth.

FIGS. 15A-15E show one example of an image fixed pattern noisecalibration and illumination non-uniformity calibration, which gives aconstant response for a uniform plane target.

FIG. 16 is a simplified block diagram of a data processing system whichcan be used to perform the methods and techniques described herein.

FIG. 17 is an example of a method of scanning teeth with an intraoralscanner to identify internal structures using a penetrative wavelength(e.g., IR and/or near-IR).

FIGS. 18A-18C illustrate one method of automatic segmentation of anear-IR image.

FIG. 18A illustrates edge detection from a penetrative scan through theteeth, taken with an intraoral scanner in the near-IR wavelength (e.g.,850 nm). FIGS. 18B and 18C shows segmentation based on the edgedetection of FIG. 18A plotted on the penetrative scan.

FIGS. 19A-19C show further segmentation of the near-IR image of FIGS.18A-18C.

FIG. 19A shows edge detection from the near-IR image taken of asubject's teeth shown in FIG. 19C. FIG. 19B shows segmentation of theimage of FIG. 19C, in which the segments (5 segments) are drawn on thenear-IR image shown in FIG. 19C.

FIGS. 20A-20C illustrate segmentation of a near-IR image of a patient'steeth. FIG. 20A is a figure showing edge detection of a near-IR image.FIG. 20B illustrates segmentation of the near-IR image, showing 18(overlapping) segments. FIG. 20C illustrates further segmentation of thenear-IR image shown in FIG. 20B.

FIGS. 21A-21C illustrate segmentation of a near-IR image of a patient'steeth. FIG. 21A shows edge detection of the near-IR image of FIG. 21C.FIG. 21B illustrates edge detection of the near-IR image shown in FIG.21C.

FIGS. 22A-22C illustrate segmentation of a near-IR image of a patient'steeth. FIG. 22A is a figure showing edge detection of a near-IR image.FIG. 22B illustrates segmentation of the near-IR image, showing 8(overlapping) segments. FIG. 22C illustrates further segmentation of thenear-IR image shown in FIG. 22B.

FIGS. 23A-23C illustrate segmentation of a near-IR image of a patient'steeth. FIG. 23A shows edge detection of the near-IR image of FIG. 23C.FIG. 23B illustrates edge detection of the near-IR image shown in FIG.23C.

FIG. 24A is a partial three-dimensional model of a patient's teethformed by segmented images, including those shown in FIGS. 18A-23C.

FIG. 24B shows a sectional view through the 3D model of FIG. 24A,showing internal structures, including the dentin.

FIG. 25A is an example of a volumetric (or “voxel”) model of a patient'sjaw and teeth, including internal structures. The internal structuresare shown as a density map within the 3D surface model. FIG. 25B is anenlarged view of the volumetric model of FIG. 25A.

FIGS. 26A-26C illustrate a method of forming a 3D surface that may beused to generate a volumetric model (showing both surface and internalstructures) of a patient's teeth.

FIGS. 27A-27G illustrate a method of generating a volumetric model of apatient's teeth using near-IR scanning in addition to surface scanning.

FIGS. 28A and 28B illustrate volumetric models of a patient's teethformed using an intraoral scanner, showing both surface features, e.g.,enamel, and internal (segmented) features, e.g., dentin.

FIG. 29A shows a partially transparent perspective view of aremovable/disposable cover configured as a trans-illumination sleevewith electrical couplings. FIG. 29B is a perspective view of the sleeveof FIG. 29A, shown solid. This sleeve is configured for use with a wandportion of an intraoral scanner; the sleeve is configured to adapt thewand to include trans-illumination with a penetrative (e.g., near-IR)wavelength.

FIGS. 30A-30C illustrate one example of a trans-illumination sleeve withelectrical couplings. FIG. 30A shows an example of a supporting frame ofthe sleeve; FIG. 30B shows the support frame with a flex circuit andconnectors coupled to the supporting frame. FIG. 30C shows the fullyassembled sleeve of FIGS. 30A-30B.

FIG. 31A shows an example of a flex circuit and connectors for use aspart of the sleeve shown in FIGS. 29A-30B. FIG. 31B is an example of adistal end portion of the flex circuit shown in FIG. 31A, including anLED housing. FIG. 31C is an example of a connector portion of a sleeve.

FIGS. 32A and 32B illustrate examples of an LED positioner and lightblocker portion of the distal end of a sleeve such as the ones shown inFIGS. 29A-30B.

DETAILED DESCRIPTION

Described herein are intraoral scanners for generating athree-dimensional (3D) model of a subject's intraoral region (e.g.,tooth or teeth, gums, jaw, etc.) which may include internal features ofthe teeth and may also include a model of the surface, and methods ofusing such scanners. For example, FIG. 1A illustrates one example of anintraoral scanner 101 that may be configured or adapted as describedherein to generate 3D models having both surface and internal features.As shown schematically in FIG. 1B, an exemplary intraoral scanner mayinclude a wand 103 that can be hand-held by an operator (e.g., dentist,dental hygienist, technician, etc.) and moved over a subject's tooth orteeth to scan both surface and internal structures. The wand may includeone or more sensors 105 (e.g., cameras such as CMOS, CCDs, detectors,etc.) and one or more light sources 109, 110, 111. In FIG. 1B, threelight sources are shown: a first light source 109 configured to emitlight in a first spectral range for detection of surface features (e.g.,visible light, monochromatic visible light, etc.; this light does nothave to be visible light), a second color light source (e.g., whitelight between 400-700 nm, e.g., approximately 400-600 nm), and a thirdlight source 111 configured to emit light in a second spectral range fordetection of internal features within the tooth (e.g., bytrans-illumination, small-angle penetration imaging, laser florescence,etc., which may generically be referred to as penetration imaging, e.g.,in the near-IR). Although separate illumination sources are shown inFIG. 1B, in some variations a selectable light source may be used. Thelight source may be any appropriate light source, including LED, fiberoptic, etc. The wand 103 may include one or more controls (buttons,switching, dials, touchscreens, etc.) to aid in control (e.g., turningthe wand on/of, etc.); alternatively or additionally, one or morecontrols, not shown, may be present on other parts of the intraoralscanner, such as a foot petal, keyboard, console, touchscreen, etc.

In general, any appropriate light source may be used, in particular,light sources matched to the mode being detected. For example, any ofthese apparatuses may include a visible light source or other (includingnon-visible) light source for surface detection (e.g., at or around 680nm, or other appropriate wavelengths). A color light source, typically avisible light source (e.g., “white light” source of light) for colorimaging may also be included. In addition a penetrating light source forpenetration imaging (e.g., infrared, such as specifically near infraredlight source) may be included as well.

The intraoral scanner 101 may also include one or more processors,including linked processors or remote processors, for both controllingthe wand 103 operation, including coordinating the scanning and inreviewing and processing the scanning and generation of the 3D modelincluding surface and internal features. As shown in FIG. 1B the one ormore processors 113 may include or may be coupled with a memory 115 forstoring scanned data (surface data, internal feature data, etc.).Communications circuitry 117, including wireless or wired communicationscircuitry may also be included for communicating with components of thesystem (including the wand) or external components, including externalprocessors. For example the system may be configured to send and receivescans or 3D models. One or more additional outputs 119 may also beincluded for outputting or presenting information, including displayscreens, printers, etc. As mentioned, inputs 121 (buttons, touchscreens,etc.) may be included and the apparatus may allow or request user inputfor controlling scanning and other operations.

Any of the apparatuses and methods described herein may be used to scanfor and/or identify internal structures such as cracks, caries (decay)and lesions in the enamel and/or dentin. Thus, any of the apparatusesdescribed herein may be configured to perform scans that may be used todetect internal structures using a penetrative wavelength or spectralrange of penetrative wavelengths. Also described herein are methods fordetecting cracks, caries and/or lesions or other internal feature suchas dental fillings, etc. A variety of penetrative scanning techniques(penetration imaging) may be used or incorporated into the apparatus,including but not limited to trans-illumination and small-anglepenetration imaging, both of which detect the passage of penetrativewavelengths of light from or through the tissue (e.g., from or through atooth or teeth).

Trans-illumination is one technique that may be used for seeing internalfeatures of teeth. Traditionally, there are 2 basic configurations fortrans-illumination through the teeth. FIGS. 2A and 2B illustrate these:a 180° configuration and a 90° configuration. Both configurations may beused for visualizing inside the teeth, and mainly through the enamel. Asshown in FIG. 2A, in the 180° configuration, a penetrative wavelength(including a spectral range of one or more penetrative wavelengths) isemitted from a light source 203 and passed from one side of the tooth201, and a sensor 205 (e.g., camera) on the opposite side detects thelight that has passed through the tooth without being scattered orabsorbed. Similarly, in FIG. 2B, the tooth 201 is illuminated by lightfrom light sources (203, 203′) on either side of the tooth 201, and thecamera 205, which is oriented 90° relative to both light sources, detectlight at the right angle to the light source. Typically,trans-illumination has been limited to the use of a single projectiontype, in order to give an image capture inside the tooth (similar to theuse of an x-ray). Described herein are methods and apparatuses forvisualization of the enamel-dentin area using a penetrative wavelength(such as between 700 to 1300 nm, 700 to 1090 nm, etc., e.g., 850 nm) andacquiring a plurality of projections or orientations from a singleposition of the scanner relative to the tooth/teeth and/or for aplurality of angles of the sensor relative to the teeth; in particularthree or more orientations or projections may be taken for each internalregion being imaged. Taking multiple (e.g., 3 or more) projections mayprovide better imaging, as it may produce multiple (e.g., 3 or more)images through the tooth from a particular location of the wand relativeto the tooth/teeth. The use of one or more 180° projection may be usefulas the light travels a shorter distance and is less scattered, howeverthe combination of multiple different projections (orientations) fromthe same location (e.g., at approximately the same scanning time, withina few milliseconds of each other) may permit the system to build avolumetric model of the enamel-dentin area.

In variations using 90 and/or 180° configuration projections, theintraoral scanner may be adapted to provide trans-illumination imagingin this configuration. For example, FIGS. 2C and 2D illustrate oneexample of a distal end of a wand of an intraoral scanner adapted tocollect trans-illumination images at 90 and 180°, in which the wand 213includes a pair of projections or wings 215 each housing a light source(LED) and camera combination 217. In FIGS. 2C and 2D, both wings and thebase of the wand may include light sources and sensors (cameras) so thatat least three trans-illumination images may be taken from a singleposition of the wand relative to the teeth, as shown in FIGS. 3A-3C. InFIG. 3A a first orientation is shown, in which the right LED 303 is on,illuminating through the tooth for detection/capture (180°) by thecamera 305 on the left. FIG. 3D is similar to FIG. 3A, showing lightapplied from the right side passing into the tooth (arrows) and eitherpassing through to the camera sensor 305 (also referred to herein as animage sensor, camera, or just “sensor”), or scattered from an internalregion. The orientation of the camera sensor and illumination source maybe switched. In FIG. 3B the left LED 303′ is on, illuminating throughthe tooth for detection/capture (180°) by the camera 305′ on the right.In FIG. 3C, both of the LEDs 303, 303′ are on, illuminating from bothright and left sides, and a camera 305″ located 90° off of the axis ofthe LEDs captures the trans-illumination image.

In general, the trans-illumination imaging data such as that describedabove can be combined with, and collected concurrently with, 3D surfacedata (e.g., 3D surface model data) of the teeth, allowing an additionallayer of data on internal structures such as caries and cracks. Further,the use of multiple projections (taken from multiple orientations) asdescribed may enable reconstruction of volumetric models internalstructures of the teeth enamel, showing features that would nototherwise be visible.

Although the 90° and 180° configurations of trans-illumination of theteeth may be useful, it may be particularly beneficial to providepenetration imaging configurations in which the angle between theemitted and received rays (vectors) is much smaller, e.g., between 0°and 30°, between 0° and 25°, between 0° and 20°, between 0° and 15°,between 0° and 10°, etc. In particular, angles between 0° and 15° (orbetween >0° and 15°) may be useful.

Trans-illumination in the 180° configuration and 90° configuration mayconstrain the movement of the intraoral scanner wand around the teethdue to their camera to light source angle constraint (as shown in FIGS.2C and 2D). Thus, also described herein are methods and apparatuses forpenetration imaging/visualization, e.g., of the enamel-dentin area,using a small angle, including between 0° and 15°. In one example, alight source (LED) emitting a penetrative spectral range (e.g., 850 nm)is used having a viewing vector at a small angle of 0°-15° relative tothe camera view angle. As mentioned, this penetration imaging may becombined with concurrent 3D surface modeling of the teeth. The relativepositions of the light source(s) and cameras(s) are typically known, andone or more penetration images may be taken at each position of thewand. Because of the small angle of the viewing vectors that may be usedby the wand, the intraoral scanning wand may be configured with just aslight curve, allowing it to fit and be easily maneuvered around theintraoral cavity, unlike wands configured to measure 90° and 180°trans-illumination, which may use a device geometry including side wingsto hold the LEDs and sensor(s) so that the wand can wrap around thetooth for the imaging (e.g., see FIG. 2C). The use of small-anglereflectance imaging may enable scanning in buccal and lingualdirections, whereas the 90 degree (trans-illumination) scanning asdescribed herein may be limited to scanning in the occlusal direction.

The use of a small angle for penetration imaging may include imaginginto the tooth using the wand in a way that enables unconstraintmovement around the tooth, and may enable capturing the internalstructure data while also scanning for 3D (surface) model data, withoutrequiring a dedicated structure and/or mode of operation. However, theuse of small angles between the emitting light and the detector(s) mayalso be complicated by direct reflections. For example, directreflection may occur in regions on the surface of the tooth in which theangle between the illumination and the imaging angles are approximatelyequal (e.g., in the cone of light and imaging NA). These directreflections may be problematic if they saturate the sensor, or if theyshow surface information but obscure deeper structure information. Toovercome these problems, the apparatus and methods of using themdescribed herein may capture and use multiple illumination orientationstaken from the same position. As used herein, in the context of ahand-held wand, taking multiple images from the same position mayeffectively mean taking multiple images at approximately the same time,so that a significant amount of movement has not occurred. For example,the images may be taken within a few milliseconds (less than 500 msec,less than 400 msec, less than 300 msec, less than 200 msec, less than100 msec, less than 50 msec, etc.) of each other, and/or correcting forsmall movements.

Alternatively or additionally, the apparatuses and/or methods may reduceor eliminate the problems arising from saturation with direct reflectionby using only the non-saturated pixels. In some variations, the surfaceinformation may be subtracted from the penetration images as part of theprocess. For example, visible light images (“viewfinder images”) orsurface imaging may be used to remove direct surface reflections.

In general, the apparatuses (e.g., systems) described herein may knowthe position of the wand at all times based on the surface scan, evenwhen taking images at different (even small angle) angles. Thus, whenperforming surface and penetrating scans concurrently or nearlyconcurrently (e.g., within 600 ms, 500 ms, 400 ms, etc. of each other),including interleaving these scans with other scanning types, theposition of the wand may be known relative to the object(s) beingscanned. Based on this information, the apparatus may estimate whichpart(s) of the multiple images or signals is/are arriving from thesurface and what is/are arriving from deeper structures.

FIG. 4A illustrates an example of a configuration of penetrative lightsources 403, 403′(e.g., penetrative spectral range light sources) andcamera(s) 405 that may be used as part of an intraoral scanner wand,shown in different positions around the target object (tooth 401). InFIG. 4A, three camera positions are shown, and each in each position thecamera is flanked by the pair of LEDs (e.g., 403 and 403′) for emittinglight in the penetrative spectral range (penetrative wavelength).Alternatively a single light source (e.g., LED) may be used instead of apair. Different images using the penetrative modality may be taken atdifferent wand positions relative to the teeth. Alternatively, the wandmay be configured with multiple imaging sensors (cameras) and multiplelight sources, allowing multiple penetration images may be taken atapproximately the same time, e.g., by turning on multiple sensors whenilluminating from one or more LED orientations (e.g., FIGS. 5G and 5E,etc.). In FIGS. 5A-5I, at least nine different orientations ofpenetration images may be taken, as shown. Alternatively oradditionally, multiple orientations may be taken sequentially, includingwithin a very short time period (e.g., within <500 ms, 400 ms, <300 ms,etc.).

FIGS. 4B-4F illustrate other emitters and detectors for use with of anyof the penetrating wavelengths that may be used to take images into theobject having semi-transparent strongly scattering regions (e.g.,teeth). These images typically collect reflective mode (e.g., light at apenetrative wavelength that has passed into the tooth, and beenscattered/reflected from internal structures so that it can be collectedby the detector. In FIG. 4B a combination of classic (e.g., 90°, 180°)trans-illumination and small-angle illumination angles are included. InFIGS. 4C-4F the angle of the ray of light emitted and collected is verysmall (e.g., around 0°) and can be collected by placing the emitter 403,403′ and detector 405 assembly (e.g., CMOS, CCD, etc.) adjacent to eachother, as shown in FIG. 4C, combined with each other, as shown in FIG.4D, or simply sharing a common or near-common beam path, as shown inFIGS. 4E and 4F, which may use reflection or waveguides to directemitted and/or received light, including the use of beam splitters(dichroic beam splitters) and/or filters.

As mentioned above, any appropriate sensor may be used, including CMOSor CCD cameras, or any other sensor that is capable of detecting theappropriate wavelength, such as near-IR wavelength detectors.

Although applying a penetrative illumination from nearby the sensor(camera) may result in the strongest illumination in the region nearestto the camera, and therefore an unequal distribution of illumination,this is surprisingly less problematic then was expected. In penetrationimaging conditions, the light generating the captured image has traveledthough the object, and the longer the path, the longer the scatteringthat will occur, resulting in a more smoothed-out illumination whencompared to direct illumination. In front illumination, as results withsmall-angle illumination, the strongest amount of light will be presentin the region nearest to the illuminator (e.g., LED), which will backscatter; this nearby region (e.g., the first 1-2 mm) is an importantregion for detecting caries. However, it may still be desirable tocompensate for the resulting non-uniform illumination profiledistribution, as discussed above.

The use of penetration imaging, and particularly small angleillumination/imaging, which may also be described as reflective imaging,may provide information about internal regions (such as cracks, caries,lesions, etc.) of the teeth that would not otherwise be available. Theinternal feature (or internal region) information may be incorporatedinto a 3D model, which may be particularly powerful when combined withsurface information (e.g., the 3D surface model or depth information).This may allow the user to capture the diagnostics data seamlesslyduring the 3D scanning procedure while allowing unconstrained movementaround the teeth to capture data from different angles, providing a 3Dmodel of the tooth interior.

Combining Surface Data with Internal Feature Data

As mentioned above, it may be particularly beneficial to combine and/orcoordinate 3D surface data with any of the internal feature data(including, but not limited to, penetration imaging data). For example,internal feature data such as penetration imaging data may be combinedwith surface data (surface imaging data) collected from the same orapproximately the same position of an intraoral scanner so that the samecoordinate system may be applied to both types of data.

As described above, a color 3D intraoral scanner such as the one shownin FIG. 1A, may be equipped with illumination devices emitting light attwo or more different spectral ranges for capturing a variety of surfaceand internal features. The data (e.g., surface data and internal featuredata) collected may be correlated and combined to form a 3D modelincluding information about lesions, decay, and enamel infractions aswell as teeth internal structure. The internal feature data may begathered by any appropriate penetrative imaging technique, including thereflective (e.g., small-angle) illumination and imaging, andtrans-illumination imaging techniques described above or by othertechniques known in the art, including, but not limited to UV/bluefluorescence and red light fluorescence.

The internal feature data may be collected (and may include lesion andinternal teeth structure images) and combined with the surface dataincluding color 3D surface model data for the teeth. The combination ofsurface and internal data may be expressed as a 3D model or 3Drendering, which may include a full color 3D data (including models andrenderings) of the lesions and tooth internal structure as well as thesurface of the teeth, gums and any other scanned portion of theintraoral region. Although in some variations the internal and surfacedata may be coextensive, in some variations the surface data may be moreextensive than the internal data; for example, the 3D model may includeinternal data for only a portion of the 3D model, while other regionsmay not include (or may include only incomplete) internal features.

In use, a 3D model of a tooth or teeth including both surface andinternal elements may be analyzed either automatically or manually, andinternal features may be identified and/or marked. For example, lesions,caries and/or cracks may be labeled, including color coding, e.g.,according to their type and level of risk they represent in one or moreimages that may be provided and/or as part of a data file that isgenerate to show these images. Alternatively or additionally, a writtentranscript/description of these findings may be provided.

An intraoral scanner for generating a 3D model including both surfaceand internal structure as described herein may include one or more imagesensors. For example, the image sensor may be configured for capturingcolor 3D (surface) images or data, and may also capture lesion and teethinternal structure images. Optionally or additionally, the system mayhave multiple sensors. The surface data may be acquired using anintraoral scanner in any appropriate manner. The intraoral scanner isgenerally configured to scan (via the wand) in both surface and internalimaging modes, including concurrently. For example, surface data may becaptured using a color intraoral 3D scanner by confocal, stereo visionor structured light triangulation or any other 3D surface scanningtechnology capable of intraoral scanning.

As illustrated in FIGS. 10A and 10B, the illumination light sources(including the lights sources for the first modality (e.g., surfacescanning), for the second modality (e.g., penetrative imaging such aspenetration imaging), and/or for the third modality (e.g., colorscanning) may be located at the front tip of the intraoral scanner wand,e.g., near the scanned objects or inside the scanner head. The front tipillumination configuration may be configurable according to theapplication needs with or without any particular light source suitablefor the desired diagnostics feature by changing the front tip. The lightsource(s) and the sensors (e.g., cameras) may be arranged in anyappropriate manner, including as shown in FIGS. 10A-10B and 4. Forexample, the light sources and cameras may be adjacent to each other. Insome variations the system or method uses miniature sensors 1005, 1007,e.g., located at the front tip in a wrap-around manner, to capturestereoscopic 3D internal feature data (e.g., images) and/or forfacilitating penetration imaging in a more efficient fashion.

As mentioned, in some variations, the lesion/internal tooth structurecapture methods may be any combination through-tooth penetrationimaging, including one or more of: trans-illumination, red light laserfluorescence and blue/UV laser fluorescence, etc. In general, theinternal feature data may be used in combination with the surface data,including the coordinate system of the surface data, to reconstruct a 3Drepresentation of the tooth structure. For example a 3D reconstructionof the tooth data may be reconstructed by an algorithm combining several(e.g., multiple) 2D images using the any of the internal feature imagingtechniques described herein, typically taken at several different anglesor orientations.

Data captured by the intraoral scanner, including in particular the 3Dmodel of the tooth/teeth having both surface and internal features, maybe stored by the device and/or transmitted to a physician, medicalrecord, dentist, or the like. For example, any of the data captured bythe intraoral scanner, i.e. a color 3D model combining the topography ofthe teeth lesions and internal teeth structure, may be maintained in adesignated patient database for longitudinal monitoring and preservationof patient's oral health. The data may be annotated (including datingand/or markings referencing internal features) or unannotated.

For example, longitudinal comparison in time may be done using the 3Dmodels described herein at one or more levels, including by comparingacross time: surface changes, visual color changes, internal/volumetricchanges, or any combination of these. For example, each can be shown asbefore and after e.g., by manual evaluation, or subtracted and comparedautomatically. In some embodiments, two or more 3D models may besuperimposed with one another on a display to highlight differencesbetween the 3D models. The superimposed models may help highlightchanges in enamel thickness, dentin volume, color, opacity, and/ordecreases/increases in caries size, for example. Optionally, a 3D modelof a patient's dentition from an earlier date may be morphed into a 3Dmodel of the patient's dentition at a later date to help highlight anychanges in the patient's dentition over time. In some embodiments, atime series of 3D models may be progressively morphed from one to thenext to provide a video or animation of the changes in the patient'sdentition. Automatic comparison may be done by applying or converting toa common coordinate system, which may in particular be done usingsurface information (e.g., based on the 3D surface model data that isincluded as part of the generated 3D volumetric model). Typically, allthree types of data (surface, color, volumetric, etc.) areinterconnected by the same coordinate system, as already describedabove. In general the method and apparatuses described herein, includingthe 3D models, may be used to predict future dental or orthodonticconditions in a patient as described, for example, in U.S. 2016/0135925,incorporated by reference in its entirety.

When comparing scans, including 3D volumetric scans, the scans may beadjusted or normalized relative to each other for automatic,semi-automatic or manual comparison. For example, a scan of the tooth orteeth (e.g., a full jaw scan, partial scan, etc.), may not be 100%repeatable, particularly to a precision higher than the voxelresolution. To compare voxel-by-voxel, a matching and/or morphingfunction may be applied to one or both scans to allow more directcomparison. For example, a matching and/or morphing function may beused. A morphing function may bring the external surfaces to match andalign, allowing a voxel-to-voxel comparison. This may also allowcomparison of full scans to partial scans.

As mentioned above, in general, captured data may be stored and saved inthe same coordinate system. Thus, surface data (including 3D surfacemodel data) may use a coordinate system (e.g., x, y, z; so that the 3Dsurface model is S(x,y,z)) and the internal feature data may use orreference the same coordinate system (e.g., so that the internal featuredata is I(x, y, z)). Thus, common features or structures may have thesame address (coordinates) between both data sets.

FIG. 6 is a diagram illustrating an example of a method for generating a3D model or rendering of a tooth or teeth using surface data andinternal feature data. In this example, a hand-held intraoral scanningwand (scanner) may first be positioned adjacent to a target intraoralregion 601 to being scanning. Once scanning is initiated, the apparatusmay collect surface data (e.g., 3D model surface data) including depthinformation in a first coordinate system 603. The surface data maytypically be collected while illuminating the sample using a firstillumination spectrum, such as visible light (e.g., monochromatic orbroadband light). Internal feature data may also be collected, e.g.,using a second illumination spectrum (which may include just a singlewavelength or small range of wavelengths) that is/are penetrative intothe tooth/teeth 605. This data may use the same coordinate system as thesurface data, which may be accomplished as described in greater detailbelow. Once collected, the data may be analyzed, and/or filtered(including subtracting, smoothing, etc.), and combined to form a 3Dmodel rendering of the intraoral cavity (e.g., tooth, teeth, gums, jaw,etc.) using both the surface data and the internal feature data 607. Forexample, when building the 3D geometry of the internal feature data(which is typically two-dimensional in nature), the algorithm may usethe reference to the known 3D surface scan to improve the accuracy ofthe internal feature data.

In general, in any of the apparatuses and methods described herein, theinternal feature data collected 605 may be used to reconstruct avolumetric model of the tooth or teeth including the internal features.In particular, tomographic reconstruction (e.g., optical tomography) maybe used. A fully volumetric modeling may be used. Typically, everypenetrating light ray can either be refracted, reflected, scatteredand/or absorbed (including combinations of these), depending on thematerial properties and the light used. In some variation, the methodsand/or apparatus may divide the volume of the tooth into small voxelsand for each voxel, estimate these four parameters (refraction index,reflection, scattering, absorption) based on the imaging data collected,using the coordinate system corresponding to the coordinate system ofthe surface data. More complex models (e.g., based on non-isotropicscattering or complex surface scattering) may also be used. Once a setof parameters for each voxel is estimated, the method or apparatus maycompare how well the captured images, fit this model. Thus in somevariations the apparatus and/or method may seek to minimize thedifference between the captured images and the modeled, predicted image.An initial guess may be built from the 3D surface capture, includingestimates of enamel parameters and width.

Alternatively or additionally, multi-surface modeling may be used.Multi-surface modeling assumes a set of material (and in some casesuniform) in optical properties, such as properties for air, dentin, andenamel (but may include more than these three). This technique may seekto find the boundaries between the materials. There are multiple ways toaccomplish this, including using techniques similar to what is describedabove for the full volumetric modeling, but without the voxelsrepresentation. Alternatively or additionally, a contour line method maybe used in which a first (e.g., air-enamel) boundary is given from the3D surface capture, and then, by finding the edges of regions in the 2Dpenetrating images, a smooth 3D surface may be approximated that bestfits this silhouette. See for example “3D Shape from Silhouette Pointsin Registered 2D Images Using Conjugate Gradient Method. AndrzejSzymczaka, William Hoffb and Mohamed Mahfouzc,” the entire contents ofwhich are incorporated herein by reference. Apart from contours, otherfeatures, like points, corners, as known in the art, may be used. Thesefeatures may be detected from the different viewpoints, and located in3D by triangulation, and are part of the boundaries.

In practice, recording the surface data and internal feature data in thesame coordinate system may be achieved by scanning both the surface andthe internal features at the same position and/or time. As mentioned, ina hand-held user controlled intraoral scanning device (e.g., wand) itmay be difficult to scan the same region at different times in differentwavelengths. Thus, any of the apparatuses and methods described hereinmay coordinate scanning at the different modalities or modes (e.g.,surface data scanning and/or internal features/penetrative datascanning).

For example, FIG. 7 illustrates one method in which the intraoralscanner alternates between surface scanning and one or more otherscanning modalities (e.g., internal feature scanning, such aspenetration imaging scanning). In FIG. 7, after positioning the scanneradjacent to the target intraoral structure to be modeled 701, the wandmay be moved over the target while the apparatus automatically scans 703the target for both surface data and internal data. As part of thismethod, the system may alternate (switch) between scanning a portion ofthe tooth using a first modality 705 (e.g., surface scanning, usingemitting light in an appropriate wavelength of range of wavelengths) tocollect surface data such as 3D surface model data and scanning with asecond modality 707 (e.g. a penetrative wavelength). After anappropriate duration in the first modality, the method and apparatus maybriefly switch to a second modality (e.g., a penetrative wavelength orrange of wavelengths) to collect internal feature data for a brief timeperiod (second duration) 707 over approximately the same region of theobject scanned in the surface mode. At the time of the switch, thecoordinate system between the two modalities is approximately the sameand the wand is in approximately the same position, as long as thesecond duration is appropriately short (e.g., less than 500 msec, lessthan 400 msec, less than 300 msec, etc., less than 200 msec, less than100 msec, less than 50 msec, etc.). Alternatively or additionally, themethod and apparatus may extrapolate the position of the wand relativeto the surface, based on the surface data information collectedimmediately before and after collecting the internal data. Thus, in anyof the methods described herein, including as shown in step 703 of FIG.7, the apparatus may interpolate the positions between each scan (e.g.,first modality scan, such as a surface scan, a second modality scan,such as a penetrative, e.g., near-IR scan or scan(s) and a thirdmodality scan, such as a color scan, etc.). This interpolation maycorrect for the small but potentially significant movement of the wandduring scanning. In particular, when coordinating between the surfaceand internal structures, in which the scanning is being manuallyperformed, interpolating (and/or extrapolating) to approximate the moreaccurate 3D position of the teeth (or of the teeth relative to thescanning wand) for each scanned image. The portion of the teeth scannedusing a penetrative wavelength may therefore be interpolatedproportionally between the surface scans done before and after thepenetrative scan(s). See, e.g., FIG. 8, described below, showing anexemplary relative timing of the scans in each mode. Alternatively oradditionally, the position of the teeth and/or wand/scanner during ascan may be extrapolated from the prior surface scan position based onthe rate of movement of the scanning wand (e.g., as estimated from therate of change across the surface from prior surface scans, and/ormotion sensor(s) in the wand). Correcting the coordinate system of eachscan in this manner (for example, in x, y and z position, andorientations angles) may allow images in different modalities to betightly registered relative to each other, regardless of how the scanneris manipulated by the user. In penetrative scans, in which multiplescans may be taken from the same relative position and used toreconstruct internal features, the accuracy of the coordinate system mayallow higher resolution modeling of the internal features.

In general, when collecting penetrative wavelength images, the lightemitted and received may have different polarizations. In the reflectivelight mode, for example when using small-angle penetration imaging, someof the energy is penetrating, but some is also reflected from thesurface. It may be preferable to block this direct surface reflection,which may be done in any appropriate manner, including usingpolarization. For example, to block the surface reflection the sample(e.g., tooth) may be illuminated with a penetrative wavelength at aspecific polarization, and this polarization may be blocked in theimaging path. This polarization may also be helpful to block directlight from the illumination source in trans-illumination (e.g., wherethere is a direct line of sight to the illuminator as in 180°trans-illumination).

Although many of the methods and apparatuses described herein includeswitching between modes to distinguish surface and internal structures,in some variations, they may be truly simultaneously detected, forexample, using a dichroic beam splitter and/or filter. Thus, byseparating out the wavelengths and/or polarization that are penetrativeand include internal reflections and/or scattering from those includingonly (or primarily) surface features, the surface data may be collectedand processed separately from the internal features, and these two datasets may be recombined later; this technique may inherently use the samecoordinate system.

For example, FIG. 2E shows a schematic of intraoral scanner configuredto do both surface scanning (e.g., visible light, non-penetrative) andpenetrative scanning using a near infra-red (NIR) wavelength (at 850 nmin this example). In FIG. 2E, the scanner includes a near-IRillumination light 289 and a first polarizer 281 and a second polarizer283 in front of the image sensor 285 to block near-IR light reflectedoff the surface of the tooth 290 (P-polarization light) while stillcollecting near-IR light scattered from internal toothstructures/regions (S-polarization light). The NIR light illuminates thetooth in P-polarization, and specular light reflected from the surfaceof the tooth, e.g., the enamel, is reflected with specular reflectionhence its P-polarization state is conserved. Near-IR light penetratingthe internal tooth features, such as the dentin, is scattered resultingin random polarization (S and P). The wavelength selective quarterwaveplate 293 does not modify the polarization of the near-IR light(e.g., it leaves the polarization state of the near-IR light beingdelivered unchanged) but changes the polarization of the returning scanlight from P to S such that only surface reflection are captured in thescan wavelength. The returning near-IR light, having a mixture of S andP polarizations, is first filtered through the polarization beamsplitter (PBS) 294 and polarizing filer 283 such that only theS-polarization is transmitted to the image sensor. Thus only the near-IRS-polarization light, coming from the tooth internal structures, iscaptured by the image sensor while specular light, having the originalp-polarization, is blocked. Other intraoral scanner configurations withor without polarization filters such as those shown in FIG. 2E may beused as part of the probe.

In FIG. 2E, the surface scan may be performed by illuminating thesurface (using the scanner illumination unit 297), illuminating inp-polarization, and the polarization is reversed by thewavelength-selective quarter waveplate 293 (transmitting S-polarizationlight to the image sensor).

As shown in FIG. 7, the scanning scheme, including the duration of thescanning modalities such as the second scanning modality to determineinternal feature data, may be manually or automatically adjusted 709.For example, scanning procedure (time sharing and sequence) may bevaried per case and the system may automatically optimize the scanningresources so as to get high-quality scans and/or more completereconstructions. The method or apparatus may determine the quality ofthe scanned data 709, such as the quality of the scanned surface data,and may adjust the scanning duration(s) (e.g., the second duration)accordingly. An estimate of quality may be made automatically, forexample, based on blurring, over- or under-saturation, etc. For example,the duration of a scanning scheme may be dynamically adjusted (e.g.,increased or decreased) based on the quality of the scans in thismodality; if the prior x scans in this modality are below a first (e.g.,minimum) quality threshold (quantifying one or more of: blurring,over-saturation, under-saturation, etc.) the scan duration for thatmodality, d_(i), may be increased. Scan time may be reduced if theduration of the scan is above a minimum duration and the quality isabove a second quality threshold (which may be the same as the firstquality threshold or greater than the first quality threshold). Reducingthe scan duration may allow the duration of other scanning modalities toincrease and/or the rate of switching between scanning modalities toincrease. Alternatively or additionally, the scan duration for amodality may be adjusted based on the completeness of the 3D model beingreconstructed. For example, when scanning a region of the 3D modelhaving a more complete surface model (e.g., regions over which thesurface model has already been made), the duration of the surface scanmay be decreased, and the duration of the penetrative scan (e.g., areflective scan using a near-IR wavelength, or a trans-illumination scanusing a near-IR wavelength) may be increased to increase the resolutionand/or extent of the internal structures. Similarly, the frequency ofthe scanning in each mode may be adjusted dynamically by the apparatus.Any of the methods and apparatuses described herein may also beconfigured to give feedback to the user to slow down or add scans from aspecific angle by showing these missing regions or angles in the 3Dgraphical display.

As illustrated in FIG. 7 (e.g., optional step 708) and in FIG. 8, morethan two scanning modalities may be used. FIG. 8 illustrates anexemplary method of operating an intraoral scanner so that it switchesbetween different scanning modalities, including surface scanning 801,laser florescence 803, color visible light scan (viewfinder) 805,penetration scanning 807, UV scanning, etc. The system may initiallyswitch between the scanning modalities with a default scanning scheme;as mentioned, the system may then (in real time) analyze the data comingfrom each of the scanning modalities and may prioritize the scanningmodalities that have less complete data, for example, by expanding thefrequency and/or duration (d) that they are scanned. In someembodiments, the system may compare the gathered data from the one ormore of the scanning modalities to predetermined data resolutionthresholds in order to determine which scanning modalities toprioritize. For example, a system may increase the frequency or durationof surface penetrative imaging after determining that sufficient surfacedata had been gathered with a surface imaging modality and that internalfeature data resolution is still insufficient. Alternatively oradditionally, in some variations scanning may be done for differentmodalities simultaneously. Once sufficient scanning area has beencompleted, the combined 3D model of the intraoral region may beassembled using the scanned data 711; alternatively the 3D model may becontinuously assembled as the scanning is ongoing. The frequency of thescanning 809 is shown by the frequency of the scan amplitude in FIG. 8;surface scans are performed at the maximum of the scan amplitude andpenetrative scans at the minimum of the scan amplitude as the depth ofthe confocal scanning increases and decreases. The frequency of thedepth scanning 809 may be increased or decreased dynamically duringscanning. For example, to allow longer scanning duration scans, or toaccommodate for a faster-moving wand/scanner by the user. In somevariations the wand may include a motion sensor (e.g., an accelerometer,etc.) to detect movement rates, and the scanning rate(s) and duration(s)may be adjusted based on the detected motion of the scanner.

As shown in FIG. 6, the resulting 3D model including surface andinternal structures may be used in a variety of ways to benefit subject(e.g., patient) health care. For example, the 3D model may be used toidentify (automatically or manually) and analyze lesions, caries and/orcracks in the teeth. The 3D model may be used, for example, to measuresize shape and location of lesion including decay, to assess the type ofdecay based on translucently, color, shape, and/or to assess the type ofsurface issues based on surface illumination e.g. cracks, decay, etc.609.

This 3D data (or data derived from it) may be monitored over time for aparticular patient 611. For example, the 3D data may be checked forchanges in shape size and type over time either visually or using analgorithm.

In general, the 3D data may be annotated. For example, after a firstscan, a clinician may mark areas of interest which may be manually orautomatically assessed in following scans. In addition the 3D data maybe used to help treat or provide treatment guidance and monitoring 613.For example, if a clinician decides to restore a tooth, the 3D datashowing surface and internal regions generated as described herein maybe used to provide reduction guidelines for the tooth to ensure theremoval of the decayed volume. During the procedure, additional (e.g.,intermediate) scans may be made to provide the doctor with furtherdirection and immediate feedback on the reduction.

FIGS. 9A and 9B illustrate one example of a 3D model 900 rendering of anintraoral region of a subject including both surface (total surface isshown in the projection of FIG. 9A) and internal structures, shown inthe enlarged region in FIG. 9B. In FIG. 9B, the darker region 903apparent from the penetration imaging using 850 nm light combined withthe 3D surface data, shows a region of interest. The region of interestmay be a carious region or a dental filing, or the like. The ability tomanipulate images like this to rotate, zoom, section and otherwise viewthe 3D model or regions of the 3D model may greatly enhance thetreatment and understanding of a subject's dental needs.

Depth Scanning

FIGS. 11A-11I illustrates one example of volumetric modeling of internaltooth structure using a penetrative wavelength such as near-IRtrans-illumination (“TI”). In this example, a lesion in the tooth may bedetected when light is bellow lesion or at the level of the lesion. Whenthe light is below the lesion, the lesion absorbs the light, thus lesionappears as dark spot in the image. In FIG. 11D, a tooth having a lesionis shown with a scanner sensor 1101 above the tooth (positioned abovethe occlusive surface of the tooth). The scanner includes one or (asillustrated in FIGS. 11D-11F) two light sources (emitters) 1105, 1105′,emitting near-IR light, as shown by the arrows. The light penetrates thetooth and the sensor 1101 detects the occlusion of light due to thelesion, as shown in FIG. 11A.

Moving the scanner with the light source upwards (i.e., moving the wandof the scanner higher along the tooth) will produce a change in thelesion image as shown in FIG. 11B. The corresponding position of thelight sources relative to the tooth is shown in FIG. 11E schematically,and in the illustration of FIG. 11H. As the scanner is moved further upthe tooth, the dark spot representing the lesion 1113 will startshrinking until completely disappearing, turning into light saturation.Finally, when the light source 1105, 1105′ is above the lesion, the darkspot is no longer present (e.g., FIG. 11C) and only the centralocclusive region (the dentin) is shown. As already discussed above, theouter surface of the tooth and gingiva may be concurrently scanned usinga separate light source, providing the 3D outer surface of the tooth,and therefore the distance from the tooth to the scanner. Thisinformation, as described above, may be used to map the lesion's depthand/or shape.

Such depth scanning may be manually or automatically performed, and maybe useful for providing a backup and/or alternative to volumetricmodeling (e.g., 0-degree volumetric modeling) of the tooth/teeth. Indeedthis vertical scanning of the teeth (which may be performed in anydirection (bottom to top of tooth, top to bottom, etc.) may be used asone type or sub-type of volumetric scanning that may provide informationon shape and position of dentin and/or lesions.

For example, the method of vertically (z-axis) scanning of theteeth/tooth with an intraoral scanner, particularly one having both apenetrative (e.g., near-IR) and surface scanning wavelength(s), mayprovide an alternative method of volumetric scanning. In general, datamay be acquired by scanning up or down (in the z-axis) the tooth/teeth.

As discussed above, one configuration for the scanning devices describedmay optically image the inside region of a tooth/teeth using, e.g.,trans-illumination (through the sides) at an angle, such as a 90° angle,between light source and camera. When a dental caries is present in thetooth, viewing the tooth with a penetrative wavelength, e.g., intrans-illumination, from above (occlusion view) may reveal the caries asan occlusive region. Depending on the relative z (depth) position of thelight source with respect to the caries, an occluded regioncorresponding to the caries will be present in the x,y image. Thusscanning through the z-axis (depth) as described above may be used todetermine one or both of z-position and shape of the caries. In somevariations, a method for scanning using a penetrative wavelength (or apenetrative and surface scanning) may begin with illuminating from thesides and imaging from above and placing light as close as possible togum line. The method may then proceed to move up along the z axis oftooth, moving away from the tooth's occlusive surface. This may allowthe light to hit a lesion from different depths (in the z-axis). Asillustrated in FIGS. 11A-11C, a caries will be initially present, and asthe scanner is drawn upwards, may shrink in the imaging plane (x,y)until it is no longer blocking the light. Any of these methods may alsocalculate or determine the z-position along the tooth as the scanner ismoved upwards, so that the relative depth on the tooth is known, andtherefore the depth of the lesion is from the enamel layer. From thisinformation, the dimensions of the lesion may also be determined (e.g.,an estimate of how far along the z-position the lesion extends), as wellas the breadth and extent (e.g., how far it extends in x,y) may also bedetermined. Along with the surface 3D model, showing the outer shape ofthe tooth, this information may be used to provide a model of the toothand the overall lesion.

Thus, using both a penetrative wavelength (e.g., near IR) and thenon-penetrative (surface scanning) wavelength, a model of both theexternal and internal structures of the tooth may be determined. Depthscans (even non-contiguous scans) along the z-axis of the tooth may beparticularly useful for determining the depths and/or dimensions ofinternal structures within the tooth/teeth. In any of the methodsdescribed herein, as discussed above, a 3D scan of the tooth may beperformed concurrently with the penetrative (including depth) scanning.

Thus, in any of the methods of scanning a tooth as described herein, themethod may include determining a depth (z) dimension for each scan,showing the relative depth of the light source(s), e.g., the near-IRlight source(s) relative to the tooth. This information may be providedby the 3D surface scan corresponding/correlating to the penetrativescan. Depth information (e.g., knowing how much the scanner has beenmoved in the z-axis) may provide substantial volumetric information.

As mentioned above, the depth (z) scanning described herein may beperformed manually or automatically. For example, this scanning may beperformed by manually scanning the wand up and along the teeth. Duringscanning both concurrent 3D surface modeling and internalmodeling/imaging may be continuously performed during scanning. Anyappropriate scanning rate (e.g., 20 scans per second) may be done. Thus,a user may scan at a reasonable speed, and output may be done inreal-time, including displaying a lesion, and/or lesions (and any otherinternal structures) may be displayed later following analysis by thesoftware. In one example, concurrent scanning may be performed so thatthe surface scanning (using a laser) may be done for an approximately 35ms period, followed by a window of 15 ms for other types of imaging,including color, near IR, etc., and repeated during the scanning period.In some examples, the near-IR scanning may be done for 5 ms within the15 ms window. Shorter sampling may be beneficial (e.g., shorter than 20ms, shorter than 15 ms, shorter than 12 ms, shorter than 10 ms, shorterthan 7 ms, shorter than 5 ms, etc.), as it may reduce smearing of theimage. However, shorter scan times may require higher energy, e.g., morepower/current to the penetrative light source. Imaging data may becollected throughout. Alternatively, scanning may be done for longer orshorter periods of time (e.g., surface scanning, near IR scanning, colorscanning, etc.), and/or at the same time (e.g., laser surface scanningand near-IR concurrently, using different emitters/detectors, forexample). In this manner, e.g., concurrent or rapid alternating (within200 ms, within 150 ms, within 100 ms, within 50 ms, etc.) of surface andpenetrative scanning, or any other different types of scanning, maypermit coordination between the surface (e.g., 3D) molding and internalstructures as described above.

Imaging Internal Structures Using Scattering Coefficients

Also described herein are methods and apparatuses for generating imagesof internal structures from within a tooth or other semi-transparent,strongly scattering object) based on a plurality of penetrative images(also referred to herein as “penetrating images”) through the object inwhich the position of the camera (relative to the object) is provided.These methods and apparatuses may therefore generate images, includingthree-dimensional models, of internal structures without requiring amodel of the external surface.

For example, described herein are methods and apparatuses, includingcomputing device readable media, for reconstructing a volumetricstructure from an object including semi-transparent strongly scatteringregions, such as a tooth. More specifically, these apparatuses (e.g.,systems) and methods may provide techniques for reconstructing an innerstructure of an object, such as the dentin in the teeth.

Generally, objects that are semi-transparent and strongly scattering toa specific wavelength can be imaged according to the methods (and usingany of the apparatuses) described herein. If the location andorientation of the camera with respect to the object is known, the innerstructure of the object can be reconstructed with a low computationalcomplexity proportional to the volume being reconstructed and the numberof images.

Any of the intraoral scanners that take images through a subject'sintraoral region (e.g., tooth or teeth, gums, jaw, etc.) describedherein and also provide information on the relative position of thescanner (e.g., the camera of the scanner taking the image), may be used.For example, returning to FIGS. 1A and 1B, FIG. 1A illustrates oneexample of an intraoral scanner 101 that may be configured or adapted asdescribed herein to generate 3D models having both surface and internalfeatures. As shown schematically in FIG. 1B, an exemplary intraoralscanner may include a wand 103 that can be hand-held by an operator(e.g., dentist, dental hygienist, technician, etc.) and moved over asubject's tooth or teeth to scan both surface and internal structures.The wand may include one or more sensors 105 (e.g., cameras such asCMOS, CCDs, detectors, etc.) and one or more light sources 109, 110,111.

In FIG. 1B, two separate light sources are shown: a first light source109 configured to emit light in a first spectral range for detection ofsurface features (e.g., visible light, monochromatic visible light,etc.) and a second light source 111 configured to emit light in a secondspectral range for detection of internal features within the tooth(e.g., by trans-illumination, small-angle penetration imaging, laserflorescence, etc., which may generically be referred to as penetrationimaging). Although separate illumination sources are shown in FIG. 1B,in some variations a selectable light source may be used. The lightsource may be any appropriate light source, including LED, fiber optic,etc. The wand 103 may include one or more controls (buttons, switching,dials, touchscreens, etc.) to aid in control (e.g., turning the wandon/of, etc.); alternatively or additionally, one or more controls, notshown, may be present on other parts of the intraoral scanner, such as afoot petal, keyboard, console, touchscreen, etc.

In addition, the wand 103 may also include one or more position and/ororientation sensors 123, such as an accelerometer, magnetic fieldsensor, gyroscope sensors, GPS etc. Alternatively or additionally, thewand may include an optical sensor, magnetic sensor, or other somecombination thereof, for detecting the relative position of the wand,and particularly of the camera(s) with respect to the object beingimaged (e.g., a tooth or teeth). Alternatively or additionally, theapparatus may detect the relative position of the wand based on thesurface images (e.g., surface scanning) and/or viewfinding scan taken asdescribed above.

In general, any appropriate light source may be used, in particular,light sources matched to the mode being detected. For example, any ofthese apparatuses may include a visible light source or other lightsource for surface detection (e.g., at or around 680 nm or otherappropriate wavelengths), a visible light source (e.g., white lightsource of light) for traditional imaging, including color imaging,and/or a penetrating light source for penetration imaging (e.g.,infrared and/or near infrared light source).

The relative positions of the light source(s) and cameras(s) aretypically known, and one or more penetration images may be taken at eachposition of the wand. The positions of the light source(s) and camera(s)can include three numerical coordinates (e.g., x, y, z) in athree-dimensional space, and pitch, yaw, and roll of the camera.

The intraoral scanner 101 may also include one or more processors,including linked processors or remote processors, for both controllingthe wand 103 operation, including coordinating the scanning and inreviewing and processing the scanning and generation of the 3D modelincluding surface and internal features. As shown in FIG. 1B the one ormore processors 113 may include or may be coupled with a memory 115 forstoring scanned data (surface data, internal feature data, etc.).Communications circuitry 117, including wireless or wired communicationscircuitry may also be included for communicating with components of thesystem (including the wand) or external components, including externalprocessors. For example the system may be configured to send and receivescans or 3D models. One or more additional outputs 119 may also beincluded for outputting or presenting information, including displayscreens, printers, etc. As mentioned, inputs 121 (buttons, touchscreens,etc.) may be included and the apparatus may allow or request user inputfor controlling scanning and other operations.

Any of the apparatuses and methods described herein may be used to scanfor and identify internal structures such as cracks, caries (decay) andlesions in the enamel and/or dentin. Thus, any of the apparatusesdescribed herein may be configured to perform scans to detect internalstructures using a penetrative wavelength or spectral range ofpenetrative wavelengths. Although a variety of penetrative scanningtechniques (penetration imaging) may be used or incorporated into theapparatus, trans-illumination and small-angle penetration imaging, bothof which detect the passage of penetrative wavelengths of light throughthe tissue (e.g., through a tooth or teeth), may be of particularinterest.

The methods and apparatuses for visualization of the enamel-dentin areausing a penetrative wavelength (such as, for example, 850 nm) describedherein may acquire a plurality of projections or orientations from asingle position of the scanner relative to the tooth/teeth; inparticular three or more orientations or projections may be taken ateach position. Taking multiple (e.g., 3 or more) projections may providebetter imaging, as it may produce multiple (e.g., 3 or more) imagesthrough the tooth from a particular location of the wand relative to thetooth/teeth.

FIG. 12 illustrates an example of a portion of a scanner configured toinclude penetration light sources 1202, 1202′ (e.g., penetrativespectral range light) and cameras that may be used as part of anintraoral scanner wand. In FIG. 12, a camera 1200 is shown that isflanked by a pair of LEDs 1202, 1202′ for emitting light in thepenetrative spectral range in substantially the same direction as thecamera towards a target T (such as a tooth 1201). A single light source1202 (e.g., LED) may be used instead of a pair. In general according tothis disclosure, the light sources of the wand are projected insubstantially the same direction as the camera, but in some embodimentsthe light sources can vary+/−15 degrees from the direction of thecamera, as described above.

FIG. 13 shows a flowchart 1300 that describes one method forreconstructing a volumetric structure from an object havingsemi-transparent strongly scattering regions for a range of radiationwavelengths. The object having semi-transparent strongly scatteringregions can be, for example, a tooth comprising an exterior enamelsurface and an interior dentin surface.

At step 302 of flowchart 1300, the method comprises taking a pluralityof images of the object with a camera in the range of radiationwavelengths, wherein lighting for the plurality of images is projectedsubstantially from a direction of the camera. In some embodiments, therange of radiation wavelengths is an infrared or near infraredwavelength. The infrared or near infrared wavelength can be used, forexample, to penetrate the semi-transparent object. In one embodiment,the lighting for the plurality of images can vary+/−15 degrees from thedirection of the camera. The plurality of images can be stored incomputer memory coupled to the camera.

Any of these methods may also include receiving location datarepresenting a location of the camera relative to the object for each ofthe plurality of images. Generally, the location data includes theposition and orientation of the camera with respect to the object. Thislocation data can be determined from the plurality of images, oralternatively or additionally, the position and orientation can bemeasured with sensors 123 on the wand (e.g., gyroscope sensors,accelerometers, GPS, etc.). Alternatively or additionally, the positionand orientation can be computed by registration of scanned surface data.In some embodiments, the location data comprises three numericalcoordinates in a three-dimensional space (e.g., x, y, and z in aCartesian coordinate system), and pitch, yaw, and roll of the camera.The location data can also be quantified as vector metrics (e.g.,rotation metrics and vector position).

At step 306 of flowchart 1300, the method further comprises generatingfor each point in a volume an upper bound on a scattering coefficientfrom the plurality of images and the location data. Each of theplurality of images may be a projection from the real world (a 3Denvironment) onto a 2D plane (the image), during which process the depthis lost. Each 3D point corresponding to a specific image point may beconstrained to be on the line of sight of the camera. The real worldposition of each 3D point can be found as the intersection of two ormore projection rays through the process of triangulation.

In step 306, an upper bound on a scattering coefficient is determinedfor each point in a volume that represents the object being scanned. Theupper bound is selected from the plurality of images for each pointusing the location data from the camera to triangulate the position ofeach point. The plurality of images produces an intensity for each pointthat is a result of the amount of light reflected by the object. Thisintensity for each point is used to generate the scattering coefficientfor each point. The upper bound on the scattering coefficient for eachpoint can be stored in memory coupled to the camera.

Generating, for each point in the volume an upper bound on thescattering coefficients may include projecting each point of a 3D gridof points corresponding to the volume of the object onto each of theplurality images using a first calibration, producing a list ofscattering coefficient values for each projected point, correcting eachscattering coefficient value on the list of scattering coefficientvalues according to a volume response, and storing a minimum scatteringcoefficient value for each grid point from the list of scatteringcoefficient values.

A number of calibrations can be performed to facilitate projecting eachpoint of the 3D grid of points onto each of the plurality of images. Forexample, in one embodiment, the first calibration may comprise a fixedpattern noise calibration to calibrate for sensor issues and imageghosts of the camera. In another embodiment, the first calibrationcomprises a camera calibration that determines a transformation for thecamera that projects known points in space to points on an image. Insome embodiments, all of the calibrations described above can beperformed prior to projecting the points onto the images.

When generating an upper bound on a scattering coefficient from thepenetrative images and location data, the upper bound on the scatteringcoefficient(s) may only be determined for points within an exteriorsurface of the object being imaged. For example, the methods describedherein can further include receiving surface data representing anexterior surface of the object (e.g., scan data representing an exterioror enamel surface of a tooth). With the exterior surface data, onlypoints within this exterior surface (e.g., internal points) can be usedto generate scattering coefficients. This may allow the imaging to focusonly on, for example, a dentin surface within an enamel surface ofteeth.

Finally, any of these methods may comprise generating an image of theobject from the upper bound of scattering coefficients for each point308. Example of generating these images are provided herein, and mayinclude forming a line and/or surface based on threshold values of thescattering coefficients or values based on the scattering coefficients.

FIG. 14 is a flowchart 400 that illustrates a method for reconstructinga volumetric structure from a tooth. The tooth can be semi-transparentin a range of radiation wavelengths. At step 402, which is optional, themethod comprises receiving, in a processor, a representation of asurface of the tooth in a first coordinate system. The representation ofthe surface of the tooth can be, for example, a 3D model of the tooththat is produced either by scanning the teeth or by taking a mold of theteeth.

The method may also include receiving, in the processor, a plurality ofimages of the tooth in the range of radiation wavelengths, the pluralityof images taken with lighting projected substantially from a directionof a camera 404. In some embodiments, the wavelength is a penetrativewavelength of the infrared or near infrared region or a range within theIR/near IR. The infrared (IR) or near infrared wavelength can be used,for example, to penetrate the tooth. The lighting for the plurality ofimages can vary+/−15 degrees from the direction of the camera. Theplurality of images can be stored in computer memory coupled to thecamera.

At step 406 the method further comprises receiving, in the processor,location data representing a location of the camera for each of theplurality of images. Generally, the location data includes the positionand orientation of the camera with respect to the object. This locationdata can be determined from the plurality of images, or alternatively,the position and orientation can be measured with sensors on the camera(e.g., gyroscope sensors, accelerometers, GPS, etc.). Alternatively oradditionally, the position and orientation can be computed byregistration of scanned surface data. In some embodiments, the locationdata comprises three numerical coordinates in a three-dimensional space(e.g., x, y, and z in a Cartesian coordinate system), and pitch, yaw,and roll of the camera. The location data can also be quantified asvector metrics (e.g., rotation metrics and vector position).

The method may also include projecting each point of a grid of pointscorresponding to a volume within the surface of the tooth onto each ofthe plurality images using a first calibration 408. The grid of pointsthat is produced may be inside of the exterior surface of the tooth. Thegrid can sit on a cubic grid, for example. Each grid point can beprojected onto each of the plurality of images using a calibration. Anumber of calibrations can be performed to facilitate projecting eachpoint of the grid onto each of the plurality of images. For example, thecalibration may comprise a fixed pattern noise calibration to calibratefor sensor issues and image ghosts of the camera. In another embodiment,the calibration may comprise a camera calibration that determines atransformation for the camera that projects known points in space topoints on an image. In some embodiments, all of the calibrationsdescribed above can be performed prior to projecting the points onto theimages.

The method may further include producing a list of intensity values foreach projected point 410. The plurality of images produces an intensityfor each point that is a result of the amount of light reflected by theobject. This intensity value for each point may be stored.

At step 412 the method may further comprise converting each intensityvalue on the list of intensity values to a scattering coefficientaccording to a volume response. This step may be performed to calibratethe intensity value for each pixel. The process calculates a scatteringcoefficient that would produce such an intensity value for each pointrelative to the position of the camera. The output is a scatteringcoefficient which normalizes the intensity according to a volumeresponse.

Finally, in FIG. 14, the method may further include storing a minimumscattering coefficient for each point into a list of minimum scatteringcoefficients 414. The method may further comprise producing an imagefrom the list of minimum scattering coefficient for each point.

As described above, the methods and techniques can include a pluralityof calibrations to project points from the real world into the pluralityof images. One such calibration is an image fixed pattern noisecalibration (PRNU) which addresses sensor issues and system ghosts thatdo not depend on the object being scanned. FIGS. 15A-E show one exampleof an image fixed pattern noise calibration, which gives a constantresponse for a uniform plane target. FIG. 15A shows an original image ofa plane uniform target, including two particles 1501, 1502 in the middleof the image. FIG. 15B shows the median image after moving the targetparallel to the plane. This causes the two particles to “disappear” fromthe image. FIG. 15C shows the image after applying a bias coefficientfigure for each pixel, which creates strong electronic noise in theimage. In FIG. 15D, a slope has been applied to each pixel, resulting ina smooth pattern given by the optics. Finally, FIG. 15E shows the finalimage after response equalization.

Another calibration that may be applied is called a camera calibration,which allows the projection of real world (3D) points to 2D imagepixels. The camera calibration determines a transformation for thecamera that projects known points in space to points on an image.

A volumetric response calibration that gives a scattering coefficientfor all points in the world given an intensity in the image within afield of view of the camera may also be applied. This calibration bringsa standard scattering coefficient to constant response anywhere in thefield of view.

Finally, a scan to world camera calibration may be applied that is arigid body transformation that converts from the scan coordinate system(of the 3D scan of the object) to the camera calibration coordinatesystem (of the 2D images of the object).

Other techniques may be used to determine the volumetric scatteringcoefficients from the penetrative images and camera positions. Forexample in some variations, back propagation may be used. Backpropagation may include estimating (e.g., tracing) rays going throughthe tooth volume and entering the camera. The actual intensitiesreaching the sensor for each ray may be taken from the penetrativeimages and camera positions and orientations. For each ray the dampingof the intensity due to scattering in the volume it passes may beestimated. For example, the transmission of light through a stronglyscattering and weakly absorbing material may be modeled using a hybridcalculation scheme of scattering by the Monte Carlo method to obtain thetemporal variation of transmittance of the light through the material. Aset of projection data may be estimated by temporally extrapolating thedifference in the optical density between the absorbing object and anon-absorbing reference to the shortest time of flight. This techniquemay therefore give a difference in absorption coefficients. For example,see Yamada et al., “Simulation of fan-beam-type opticalcomputed-tomography imaging of strongly scattering and weakly absorbingmedia,” Appl. Opt. 32, 4808-4814 (1993). The volumetric scattering maythen be estimated by solving for the actual intensities reaching thesensor.

Any of the methods described herein may be performed by an apparatusincluding a data processing system (or subsystem), which may includehardware, software, and/or firmware for performing many of these stepsdescribed above, including as part of a processor of an intraoralscanner (see, e.g., FIG. 1B). For example, FIG. 16 is a simplified blockdiagram of a data processing sub-system 500. Data processing system 500typically includes at least one processor 502 which communicates with anumber of peripheral devices over bus subsystem 504. These peripheraldevices typically include a storage subsystem 506 (memory subsystem 508and file storage subsystem 514), a set of user interface input andoutput devices 518, and an interface to outside networks 516, includingthe public switched telephone network. This interface is shownschematically as “Modems and Network Interface” block 516, and iscoupled to corresponding interface devices in other data processingsystems over communication network interface 524. Data processing system500 may include a terminal or a low-end personal computer or a high-endpersonal computer, workstation or mainframe.

The user interface input devices may include a keyboard and may furtherinclude a pointing device and a scanner. The pointing device may be anindirect pointing device such as a mouse, trackball, touchpad, orgraphics tablet, or a direct pointing device such as a touchscreenincorporated into the display. Other types of user interface inputdevices, such as voice recognition systems, may be used.

User interface output devices may include a printer and a displaysubsystem, which includes a display controller and a display devicecoupled to the controller. The display device may be a cathode ray tube(CRT), a flat-panel device such as a liquid crystal display (LCD), or aprojection device. The display subsystem may also provide nonvisualdisplay such as audio output.

Storage subsystem 506 may maintain the basic programming and dataconstructs that provide the functionality of the present invention. Themethods described herein may be configured as software, firmware and/orhardware, and (of software/firmware) may be stored in storage subsystem506. Storage subsystem 506 typically comprises memory subsystem 508 andfile storage subsystem 514.

Memory subsystem 508 typically includes a number of memories including amain random access memory (RAM) 510 for storage of instructions and dataduring program execution and a read only memory (ROM) 512 in which fixedinstructions are stored. In the case of Macintosh-compatible personalcomputers the ROM would include portions of the operating system; in thecase of IBM-compatible personal computers, this would include the BIOS(basic input/output system).

File storage subsystem 514 may provide persistent (nonvolatile) storagefor program and data files, and may include at least one hard disk driveand at least one floppy disk drive (with associated removable media).There may also be other devices such as a CD-ROM drive and opticaldrives (all with their associated removable media). Additionally, thesystem may include drives of the type with removable media cartridges.One or more of the drives may be located at a remote location, such asin a server on a local area network or at a site on the Internet's WorldWide Web.

In this context, the term “bus subsystem” may be used generically so asto include any mechanism for letting the various components andsubsystems communicate with each other as intended. With the exceptionof the input devices and the display, the other components need not beat the same physical location. Thus, for example, portions of the filestorage system could be connected over various local-area or wide-areanetwork media, including telephone lines. Similarly, the input devicesand display need not be at the same location as the processor, althoughit is anticipated that the present invention will most often beimplemented in the context of PCS and workstations.

Bus subsystem 504 is shown schematically as a single bus, but a typicalsystem has a number of buses such as a local bus and one or moreexpansion buses (e.g., ADB, SCSI, ISA, EISA, MCA, NuBus, or PCI), aswell as serial and parallel ports. Network connections are usuallyestablished through a device such as a network adapter on one of theseexpansion buses or a modem on a serial port. The client computer may bea desktop system or a portable system.

Scanner 520 may correspond to the wand and other components responsiblefor scanning casts of the patient's teeth obtained either from thepatient or from an orthodontist and providing the scanned digital dataset information to data processing system 500 for further processing. Ina distributed environment, scanner 520 may be located at a remotelocation and communicate scanned digital data set information to dataprocessing system 500 over network interface 524.

Various alternatives, modifications, and equivalents may be used in lieuof the above components. Additionally, the techniques described here maybe implemented in hardware or software, or a combination of the two. Thetechniques may be implemented in computer programs executing onprogrammable computers that each includes a processor, a storage mediumreadable by the processor (including volatile and nonvolatile memoryand/or storage elements), and suitable input and output devices. Programcode is applied to data entered using an input device to perform thefunctions described and to generate output information. The outputinformation is applied to one or more output devices. Each program canbe implemented in a high level procedural or object-oriented programminglanguage to operate in conjunction with a computer system. However, theprograms can be implemented in assembly or machine language, if desired.In any case, the language may be a compiled or interpreted language.Each such computer program can be stored on a storage medium or device(e.g., CD-ROM, hard disk or magnetic diskette) that is readable by ageneral or special purpose programmable computer for configuring andoperating the computer when the storage medium or device is read by thecomputer to perform the procedures described. The system also may beimplemented as a computer-readable storage medium, configured with acomputer program, where the storage medium so configured causes acomputer to operate in a specific and predefined manner.

FIGS. 26A-26C and 27A-27G illustrate steps that may form part of amethod of forming a 3D volumetric model of a patient's teeth and may beused for one or more treatments using the methods and apparatusesdescribed above. In any of these methods, an intraoral scanner 2801capable of measuring both surface (including, in some variations color,e.g., R-G-B color) and internal structures may be used to scan thepatient's teeth (e.g., taking images and scans of the jaw, including theteeth). The apparatus may scan in different modalities, includingsurface (non-penetrative or not substantially penetrating, e.g., visiblelight, white light) and penetrative (e.g., near IR/IR) wavelengths.Scanning typically includes scanning from multiple positions around theoral cavity and assembling the resulting images into a three-dimensionalmodel of the teeth, e.g., by solving the relative position of the scansrelative to the jaw (FIG. 26C). The surface scanning may be used toconstruct a model (e.g., a 3D digital model, and/or renderings) of theouter surface of the jaw/teeth 2803, as shown in FIG. 26C.

In any of these methods and apparatuses described herein, internalstructures within the teeth may be formed or modeled to form avolumetric model of the teeth including the internal structures that areextracted from the penetrative scans (e.g., near-IR and/or IR scans), asillustrated in FIGS. 27A-27G. FIGS. 26A-27G describe one method ofreconstructing internal structures by using scattering coefficients(other methods may be used alternatively or additionally). In FIG. 27A,a grid is constructed of points representing the inner volume of thejaw/teeth. All of the grid points are projected onto the penetrative(e.g., near-IR) images taken, and all pixel positions may be saved foreach of the grid points, as shown in FIG. 27B. For each pixel positionand grid position, the apparatus may calculate the scatteringcoefficient which would result in the gray level of pixel observed, asgraphically illustrated in FIG. 27C. In the figures (e.g., FIG. 27C),the eye may represent the viewing angle of the sensor (e.g., camera).For each grid point, the apparatus may take the minimal scatteringcoefficient that is calculated (FIG. 27D). The grid of points withcorresponding minimal scattering coefficients may then provide a volume2909 that may be sampled at the grid points based on thresholds orcorrelations (e.g., iso-surfaces) of minimal scattering values, as shownin FIG. 27E. FIG. 27G shows an iso-surface 2911 created by identifying aconstant value of the density function sampled. FIG. 27F is an enlargedview of the same region of the teeth, showing both the iso-surface fromFIG. 27G as well as a ghosted image (partially transparent) of theenamel 2915 around the iso-surface. This iso-surface may representdentin and (as described below) dental caries extending from the outersurface of the tooth toward the dentin.

In the example shown in FIG. 27F, the iso-surface shows thedentin-enamel transition 2911 visible beneath the enamel 2915. Theexample in FIG. 27F also indicates a dental caries shown in circledregion 2913. In this example, the dental caries (similar to the dentin)appears as an iso-surface within or surrounded by the enamel. The dentalcaries may be distinguished because it extends from the inner, dentinregion to an outer surface of the tooth. Since the methods andapparatuses described herein may accurately reconstruct both the outersurface and the inner structures, this characteristic configuration(showing an arm or extension extending from the outer surface throughthe IR/near-IR transparent enamel) may be used to identify dentalcaries. In FIG. 27F a likely dental caries region is circled 2913,showing an extension or bridge between two teeth in a region where thesurface scan shows that the teeth are actually separate. Thus, combiningthe surface scan with the internal scanning (e.g., from the IR/near-IRimages) may allow for corrections in the internal data due to errorsthat may occur because of the limited view angles or the like. Any ofthe apparatuses and methods described herein may be configured toautomatically or semi-automatically identify these regions orirregularities corresponding to dental caries and the like. They may behighlighted in the model, image or representation of the teeth, and/or aflag, alert or other notification, along with a putative location, maybe presented, transmitted and/or stored. Alternatively or additionally,the threshold(s) used to determine the iso-surfaces may be chosen todistinguish between the one or more internal features such as thedentin, caries, fillings, cracks, etc.

Alternatively or additionally, the apparatus may automatically (orsemi-automatically) determine and distinguish internal structures withinthe teeth based on the shape of the iso-surfaces and/or their relativeposition(s) within the teeth. As mentioned above, caries may have asimilar densities (e.g., scattering coefficients) compared to dentin.However, the morphology of the caries may distinguish them from dentin.The apparatus may detect ‘arms’ or appendages of material having adensity (e.g., scattering coefficients) similar to that for dentin, butextending from the out surface of the enamel. Since the outer surface ofthe teeth may be well characterized in addition to the internalstructures, the extent of a caries may be determined by mapping theouter surface of the iso-density map for regions extending from theouter surface toward a larger, defined internal dentin pattern. Theborder between the dentin and the internal extent of the caries may bedetermined by approximating the continuous surface of the dentin,including the region around the “projecting” region and/or looking atthe rate of change of direction of the surface of the dentin. Otherinternal structures, such as fillings, cracks and the like may bedistinguished based on their scattering coefficient value ranges, and/orbased on their position or morphology. The apparatus may display them indifferent colors, annotations, etc.

Thus, in any of these methods and apparatuses, the scanner may seeinside the enamel and reconstruct the margin line. In addition, the useof additional wavelengths (e.g., green light) or even differentradiation modalities (e.g., ultrasound) imaging through the flesh may bepossible, allowing construction of margin lines and even teeth roots,and/or helping to distinguish structures such as dental caries from thedentin or other internal structures.

The resulting volumetric 3D model of the teeth may be used toreconstruct teeth base on the histological teeth. As described, thevolumetric model may be used to create dental prosthetics (implants,etc.) that have a more realistic appearance and/or a better fit.

Further, the methods and apparatuses described herein may permit a user(e.g., dentist, physician, dental technician, etc.) to follow the teethover time, including tracking dentin, caries, etc., and general dentalhealth by comparing models taken over time. For example, time-lapsevideos (images) may be constructed. FIG. 28A shows an example of avolumetric reconstruction taken at a first time, showing the dentin 3001(solid) and enamel 3003 (made slightly transparent). FIG. 28B showanother example of a volumetric model of teeth showing the dentin 3001and enamel 3003.

The volumetric model may include width information may provide estimatesof wear over time as well. For example, changes in the enamel width overtime and over different regions of the teeth may be easily tracked. Byknowing the enamel width we can estimate the tooth wear and provide asnap shot of the severity of wear.

Segmentation and Classification

Any appropriate method and/or apparatus (e.g., systems, devices,software, etc.) for generating images of internal structures from withina tooth (or other semi-transparent, strongly scattering object) may beused. For example, alternatively or additionally to the use ofscattering coefficients as discussed above, any of the apparatuses andmethods described herein may use the two-dimensional penetrative imagesalong with position and/or orientation information about the intraoralscanner relative to the object being imaged (e.g., the teeth) to segmentthe two-dimensional penetrative images and form a three-dimensionalmodel of the teeth including one or more internal structures within theobject. A penetrative image may refer to images taken with a near-IRand/or IR wavelength, revealing internal structures within the object(e.g., tooth). The position and/or orientation of the scanner may be aproxy for the position and/or orientation of the camera taking theimages which is on the scanner (e.g., on a handheld wand).

The apparatuses and methods described herein may construct athree-dimensional (3D) volumetric model of the teeth from segmentedtwo-dimensional (2D) images. These methods and apparatuses may alsosegment the 3D model of the teeth.

In general, the methods and apparatuses described herein allow for thedirect segmentation of the penetrative images. This may allow for theidentification of dentin within the teeth, including the location andmorphology of the dentin, as well as the identification and location ofcracks, lesions, and/or caries in the teeth, including in the dentin.The use of segmentation may allow for reconstruction of a volumetricmodel based on the penetrative images and the knowledge of the cameraposition corresponding to the penetrative images. A volumetric model ofteeth can be segmented and these segments (relating to differentinternal structures of the tooth) may be projected back to the imagesand/or combined with a surface model of the teeth (e.g., the outer toothsurface), allowing projections onto the surface images and bettersegmentation of the inner structures of teeth.

Thus, penetrative images taken through the teeth with a penetrativewavelength (e.g., near IR and/or IR), may include inner teeth structuresand/or 3D data. These images may be taken using any of the dentalscanners described herein, and the teeth volume may be segmented intodifferent regions according to opacity, color, and other properties ofthe images and 3D data. These regions can be for example: healthyenamel, dentin, lesion, dental filling(s), etc. The segmentation can bedone on 2D images or on volumetric models. The segmentation can be usedto classify the images and/or the 3D models according to the presence ofdifferent segments. A user may be able to detect by this segmentationmanually or automatically (or semi-automatically) to classify differentinternal structures, such as: dental caries, enamel erosion, and otherdental issues. Further, the images or models may be used to measureinternal regions of a tooth or multiple teeth segments for better dentaltreatments, including aligning teeth or other treatment planning. Forexample, a user may be able to locate dental lesion in an accuratefashion to plan accurate filling with minimal enamel extraction. Thus,the use of segmentation as described herein may permit the capture ofinner teeth structure without ionizing radiation, as is currently usedwith X-rays. Dental issues may be presented on 3D volumetric model.Further, as will be described in detail below, segmentation andclassification of internal structures may be automatized. Finally, exactmeasurements of internal structures may be taken for better treatmentplanning.

FIG. 17 illustrates an example of a data flow for scanning teeth with anintraoral scanner to identify internal structures. In FIG. 17, themethod shown includes three parts. First, the teeth may be scanned withan intraoral scanner 1701 (or any other scanner) configured to providepenetrative scans into the teeth using an optical (e.g., IR, near IR,etc.) wavelength or range of wavelengths. Any of these scanners may alsoconcurrently scan to determine a surface features (e.g., via one or morenon-penetrative wavelengths), color, etc., as described above. Duringscanning, a plurality of penetrative scans 1703, 1703′ are taken, andthe position of the camera 1705, 1705′ (e.g., x,y,z position and/orpitch, roll, yaw angles) may be determined and/or recorded for eachpenetrative image. In some variations, the surface of the teeth may alsoand concurrently be imaged, and a 3D surface model of the teeth 1707determined, as described above. In this example, the patient's teeth maybe scanned, for example, with an intraoral 3D scanner 1702 that iscapable of imaging the inner teeth structure using, for example, nearinfra-red imaging. The location and orientation of the camera may bedetermined, in part, from the 3D scanning data and/or the 3D teethsurface model 1707.

Thereafter, the penetrative images may be segmented 1711. In thisexample, segmentation may be done in one of two ways. On the inner teethstructure images, the images may be segmented using contour finding1713, 1713′. Machine learning methods may be applied to further automatethis process. Alternatively or additionally, near images (where theircamera position is close) may be used to decide on close features, andalso project features from the 3D model back to the images in order tolocate correctly segments like enamel. The method may also includeprojecting pixels from the inner teeth images back to the teeth andcalculating a density map of inner teeth reflection coefficient.Enclosing surfaces of different segments may be found or estimated byusing iso-surfaces or thresholds of the density map and/or by machinelearning methods. In addition, segmenting the images and projecting thesegments back to a model (such as the 3D surface model, e.g., projectingback to the world), may be used to find a segment by the intersection ofthe segment projections and the teeth surface.

The results may be displayed 1717, transmitted and/or stored. Forexample, the results may be displayed by the scanning system during theintraoral scanning procedure. The results may be shown by images withenclosing contours for different segments, a 3D density map, etc. In theexample shown in FIG. 17 a density map 1715, representing the dentinbeneath the enamel on the outer surface, is shown. This image may becolor coded to show different segments. In this example, internalsegments (structures) are shown within the 3D surface model (which isshown transparent); not all teeth have been scanned with penetrativeimages, thus, only some are shown. Alternative views, sections, slices,projections or the like may be provided. In FIG. 17, the example imageincludes artifacts that are present outside of the teeth 1716; these maybe removed or trimmed, based on the surface model 1718.

A segment may mark each pixel on the image. Internal structures, such asdentin, enamel, cracks, lesions, etc. may be automatically determined bysegmentation, and may be identified manually or automatically (e.g.,based on machine learning of the 3D structure, etc.). Segments may bedisplayed separately or together (e.g., in different colors, densities,etc.) with or without the surface model (e.g., the 3D surface model).

Thus, in FIG. 17, the patient is initially scanned with a 3D scannercapable of both surface scanning and penetrative scanning (e.g., near IRimaging), and the orientation and/or position of the camera is known(based on the position and/or orientation of the wand and/or the surfacescans). This position and orientation may be relative to the toothsurface. The method and apparatus may therefore have an estimate of thecamera position (where it is located, e.g., x,y,z position of thecamera, and its rotational position).

In general, penetrative images (e.g., near IR or IR images) may besegmented automatically. FIGS. 18A-18C illustrate a first example ofautomatic segmentation of a near-IR image. FIG. 18A, shows a firstautomatic segmentation of the outer surface of the teeth, determined by,e.g., edge detection. In FIG. 18A, the edges 1803 of the outer perimeterare shown. In this example, only a first level of edge detection wasperformed, looking for the outer perimeter. In FIGS. 18B and 18C, acontinuous edge region 1805 is shown, derived from the edge detection,and mapped onto the near-IR image (original image). FIGS. 19A-19C showthe identification and mapping of other edges from the same image. FIG.19A shows just the edges detected using a threshold setting value fromthe near-IR image (e.g., FIG. 19C). In FIG. 19B five (overlapping 1905)segments, 0-4, are traced from the detected edges by forming continuouslines. The different segments are shown color coded, and a color keyidentifying the segments is shown on the right. From the near-IR imagesthe apparatus can automatically segment the images. In FIGS. 18A-18C and19A-19C, the different segments are marked and may correspond todifferent regions (or different internal structures) on image. Whenmultiple images are analyzed, these putative segments may bere-projected back to a 3D model and/or shown in the images. FIGS.20A-20C and 21A-21C illustrate other examples of near-IR images from thesame patient shown in FIGS. 18A-19C, illustrating segmentation based onedge detection and identification of presumptive continuous line regionsfrom the detected edges. In FIG. 21A-21C, another region of the teethfrom the same patient are shown; eight segments (0-7) have beenidentified in this image, as shown in FIG. 21B. FIG. 21A shows the edgedetection of the original image, shown in FIG. 21C. FIGS. 22A-22Cillustrate segmentation of another region of the patient's teeth. FIG.22A shows the detected edges from the original near-IR image. FIGS. 22Band 22C show eight segments (0-7) identified on the near-IR image.Similarly, FIGS. 23A-23C illustrate segmentation of another region ofthe patient's teeth; FIG. 23A shows the detection of edges, FIG. 23Bshows segments identified from these edges, and FIG. 23C shows theoriginal near-IR image.

The segmented images, such as those shown in FIGS. 18A-23C may be usedto form a model of the internal structures of the scanned object (e.g.,teeth). The surface 3D model may also be used. For example, FIGS.24A-24B show a three-dimensional model of a region of the patient'steeth formed by segmented images, including those shown in FIGS.18A-23C. In FIG. 24A, the 3D reconstruction includes the outer surfaceof the teeth (shown as partially transparent), and different internalsegments may be shown in different colors and/or transparencies. Forexample, In FIG. 24A, the dentin (inner part of teeth) 2404 is shownwithin the teeth 2405 boundary. In FIG. 24A the segment showing thedentin is a surface (volume in FIG. 24B), but it may also be shown as adensity map, as will be illustrated in FIGS. 25A and 25B, below. Theresulting 3D volume including the segmented images may be iterativelyused to take images through the resulting volume, which may be‘projections’ that can be compared directly to the original near-IRimages, and this comparison may be used to modify the model. Thisprocess may be repeated (iterated) to refine the model, which mayprovide better segmentation of images.

As described above, segmentation may include edge detection. Anyappropriate edge detection method may be used, including machinelearning. Segmentation of the plurality of near-IR images may be used inconjunction with the positional information of the camera to reconstructthe volume. Since a plurality of different sections (different conics)are known, and segmented, the resulting segments inside of all of theprojections of the conics, from different positions are known andintersections of these segments may therefore be determined. Thisprocess may be made easier by using the outer surface boundary of theteeth, which may be provided by the surface imaging and/or the 3D model.As described above, this process may be iterative; the method may usethe 3D data to project simulated penetrative (e.g., near-IR) images thatmay be compared to the original to improve segmentation and derive asecond, evolved, model of the internal structures. Similarly, segmentsor segment regions outside of the teeth surface 2407 may be removed.

The model of the tooth, including internal structures, may be displayedin a variety of ways, as mentioned above. FIG. 24B shows a sectionthrough the teeth, showing the internal structures, including the dentin2404 and the enamel thickness between the outer surface 2405 and thedentin 2404.

FIGS. 25A and 25B show an reconstruction of the teeth including internalstructures (also shown in FIG. 17, above). In this example, the internalstructures are shown by a density mapping (e.g., segments). For example,the dentin 2505 is shown in more detail within a portion of the surfacemodel 2503 in FIG. 25B. The outer surface of the teeth may also beidentified as a segment (as shown in FIGS. 25A and 25B), and there isnear-perfect agreement between the segmented outer surface and the outersurface as determined from surface imaging in this example.

Sleeves for Intraoral Scanners Having Trans-Illumination

Any of the devices described herein may also include a sleeve or sleevesthat is configured to protect the intraoral scanner wand, but may alsobe configured to extend the functionality and/or adapt the scanner foruse with a penetrative wavelength, including trans-illumination. Thesleeve illustrated in FIGS. 29A-31B is an example of a sleeve that maybe used as a barrier (e.g., sanitary barrier) to prevent contaminationof the wand portion of the intraoral scanner, as the scanner may be usedwith different patients, and also as an adapter for providingtrans-illumination by IR/near-IR wavelength imaging. The sleeve in thesefigures is configured as a trans-illumination sleeve with electricalcouplings. For example, the sleeves described herein may include bothpenetrative wavelength illumination (e.g., near-IR and/or IR LEDs) andone or more sensors (e.g., CCDs) or may use the same cameras already onthe wand.

In FIG. 29A, the wand of an intra-oral scanner is shown with a sleeve3101 disposed around the end of the wand 3105; the sleeve is shown assemi-transparent, so that the internal structures (connectors) arevisible. FIG. 29B shows just the sleeve 3105 for the intraoral scanner(wand) shown as solid. In general, the sleeve 3105 slips over the end ofthe wand so that the light sources and cameras (sensors) already on thewand are able to visualize through the sleeve, and so that theelectrical contacts 3123, which may provide control, power and/or datatransmission to the LEDs and/or sensors 3125 integrated into or on thesleeve. The sleeve includes a pair of wing regions 3103 on oppositesides, facing each other and extending from the distal end of the wandwhen the sleeve is placed over the wand.

The sleeve 3101 may be held on the end of the wand by friction or by anattachment (not shown). Consequently, the sleeve may be readily removedfrom the wand and a new sleeve can be placed on the wand each time thescanner is used on a different patient. In this example, the sleeve maybe configured to transmit IR (e.g., near IR), and thus may include oneor more projections 3103 (e.g., for trans-illumination, etc.) as shownin FIG. 29B. The electrical contacts and connector integrated into thesleeve may adapt the scanner for IR/near-IR trans-illumination.

Thus, the sleeve may include circuitry (e.g., flex circuitry) connectingto an LED illumination (IR/near-IR) source and/or one or more sensors,particularly for trans-illumination. FOR example, FIGS. 30A-30C. FIG.30A shows an example of the frame 3201 of the sleeve, which may be rigidor semi-rigid. The frame may support the flex circuitry 3203 (shown inFIG. 30B) and/or connectors 3205 and may also provide shielding (e.g.,blocking light). The frame and circuitry may be covered by a flexibleouter sleeve 3207 as shown in FIG. 30C.

The sleeve may be assembled by injection molding of the component parts,including the overall sleeve, windows for illumination and imagecapture, connectors for the circuitry and one or more LED holdingregions (e.g., injection of an IR and visible-light transparent materialforming windows through the sleeve, then injection of the rigid sleevematerial). The flex circuitry may then be positioned, and LEDencapsulation may be placed, using mold locators. The flexible outersleeve may then be injected.

FIGS. 31A-31C illustrate more detailed views of the flex circuitry 3301,connectors 3303 and LED holders/shields 3305. FIGS. 32A-32B illustrateexamples of the LED positioner and light blocker portion of the distalend of the sleeve. The example shown in FIG. 32A includes a supportframe or arm 3404 that extends down and includes a light shroud orblocker region 3406 encapsulating a portion of the LED. Exemplarydimensions are shown.

When a feature or element is herein referred to as being “on” anotherfeature or element, it can be directly on the other feature or elementor intervening features and/or elements may also be present. Incontrast, when a feature or element is referred to as being “directlyon” another feature or element, there are no intervening features orelements present. It will also be understood that, when a feature orelement is referred to as being “connected”, “attached” or “coupled” toanother feature or element, it can be directly connected, attached orcoupled to the other feature or element or intervening features orelements may be present. In contrast, when a feature or element isreferred to as being “directly connected”, “directly attached” or“directly coupled” to another feature or element, there are nointervening features or elements present. Although described or shownwith respect to one embodiment, the features and elements so describedor shown can apply to other embodiments. It will also be appreciated bythose of skill in the art that references to a structure or feature thatis disposed “adjacent” another feature may have portions that overlap orunderlie the adjacent feature.

Terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention.For example, as used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, steps, operations, elements, components, and/orgroups thereof. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items and may beabbreviated as “/”.

Spatially relative terms, such as “under”, “below”, “lower”, “over”,“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if a device in thefigures is inverted, elements described as “under” or “beneath” otherelements or features would then be oriented “over” the other elements orfeatures. Thus, the exemplary term “under” can encompass both anorientation of over and under. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly. Similarly, the terms“upwardly”, “downwardly”, “vertical”, “horizontal” and the like are usedherein for the purpose of explanation only unless specifically indicatedotherwise.

Although the terms “first” and “second” may be used herein to describevarious features/elements (including steps), these features/elementsshould not be limited by these terms, unless the context indicatesotherwise. These terms may be used to distinguish one feature/elementfrom another feature/element. Thus, a first feature/element discussedbelow could be termed a second feature/element, and similarly, a secondfeature/element discussed below could be termed a first feature/elementwithout departing from the teachings of the present invention.

Throughout this specification and the claims which follow, unless thecontext requires otherwise, the word “comprise”, and variations such as“comprises” and “comprising” means various components can be co-jointlyemployed in the methods and articles (e.g., compositions and apparatusesincluding device and methods). For example, the term “comprising” willbe understood to imply the inclusion of any stated elements or steps butnot the exclusion of any other elements or steps.

As used herein in the specification and claims, including as used in theexamples and unless otherwise expressly specified, all numbers may beread as if prefaced by the word “about” or “approximately,” even if theterm does not expressly appear. The phrase “about” or “approximately”may be used when describing magnitude and/or position to indicate thatthe value and/or position described is within a reasonable expectedrange of values and/or positions. For example, a numeric value may havea value that is +/−0.1% of the stated value (or range of values), +/−1%of the stated value (or range of values), +/−2% of the stated value (orrange of values), +/−5% of the stated value (or range of values), +/−10%of the stated value (or range of values), etc. Any numerical valuesgiven herein should also be understood to include about or approximatelythat value, unless the context indicates otherwise. For example, if thevalue “10” is disclosed, then “about 10” is also disclosed. Anynumerical range recited herein is intended to include all sub-rangessubsumed therein. It is also understood that when a value is disclosedthat “less than or equal to” the value, “greater than or equal to thevalue” and possible ranges between values are also disclosed, asappropriately understood by the skilled artisan. For example, if thevalue “X” is disclosed the “less than or equal to X” as well as “greaterthan or equal to X” (e.g., where X is a numerical value) is alsodisclosed. It is also understood that the throughout the application,data is provided in a number of different formats, and that this data,represents endpoints and starting points, and ranges for any combinationof the data points. For example, if a particular data point “10” and aparticular data point “15” are disclosed, it is understood that greaterthan, greater than or equal to, less than, less than or equal to, andequal to 10 and 15 are considered disclosed as well as between 10 and15. It is also understood that each unit between two particular unitsare also disclosed. For example, if 10 and 15 are disclosed, then 11,12, 13, and 14 are also disclosed.

Although various illustrative embodiments are described above, any of anumber of changes may be made to various embodiments without departingfrom the scope of the invention as described by the claims. For example,the order in which various described method steps are performed mayoften be changed in alternative embodiments, and in other alternativeembodiments one or more method steps may be skipped altogether. Optionalfeatures of various device and system embodiments may be included insome embodiments and not in others. Therefore, the foregoing descriptionis provided primarily for exemplary purposes and should not beinterpreted to limit the scope of the invention as it is set forth inthe claims.

The examples and illustrations included herein show, by way ofillustration and not of limitation, specific embodiments in which thesubject matter may be practiced. As mentioned, other embodiments may beutilized and derived there from, such that structural and logicalsubstitutions and changes may be made without departing from the scopeof this disclosure. Such embodiments of the inventive subject matter maybe referred to herein individually or collectively by the term“invention” merely for convenience and without intending to voluntarilylimit the scope of this application to any single invention or inventiveconcept, if more than one is, in fact, disclosed. Thus, althoughspecific embodiments have been illustrated and described herein, anyarrangement calculated to achieve the same purpose may be substitutedfor the specific embodiments shown. This disclosure is intended to coverany and all adaptations or variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, will be apparent to those of skill in theart upon reviewing the above description.

What is claimed is:
 1. A sleeve device for an intraoral scanner, thedevice comprising: a sleeve body configured to couple with a wand of anintraoral scanner, the sleeve body comprising a light-passing region ata distal end of the sleeve body configured to allow near-infrared(near-IR) light to pass; a first wing extending from the distal end ofthe sleeve body adjacent to the light-passing region; a second wingextending from the distal end of the sleeve body adjacent to thelight-passing region; one or more near-IR light sources in the firstwing configured to emit near-IR light; and one or more electricalcontacts within the sleeve and configured to make an electrical contactwith the wand to receive energy from the wand to power the one or morenear-IR light sources.
 2. The sleeve of claim 1, wherein the sleeve bodyis rigid.
 3. The sleeve of claim 1, wherein the first and second wingsare opposite from each other and extend in a proximal to distaldirection adjacent to the light-passing region.
 4. The sleeve of claim1, wherein the sleeve comprises circuitry connected to the one or morenear-IR light sources.
 5. The sleeve of claim 1, wherein at least one ofthe near-IR light sources in the first wing is at least partiallyencapsulated in the first wing to block a portion of the near-IR lightsource.
 6. The sleeve of claim 1, wherein the one or more near-IR lightsources on the first wing are between about 6.5 and 11.5 mm from thelight-passing region at the distal end of the sleeve body.
 7. The sleeveof claim 1, further comprising one or more additional near-IR lightsources on the second wing.
 8. The sleeve of claim 1, further comprisinga near-IR sensor on the first wing or the second wing.
 9. The sleeve ofclaim 1, wherein the sleeve housing is configured to be held on a distalend of the wand by an attachment.
 10. The sleeve of claim 1, wherein thesleeve housing is configured to be held on a distal end of the wand byfriction.
 11. The sleeve of claim 1, wherein the light-passing regioncomprises an opening through the sleeve.
 12. The sleeve of claim 1,wherein the first wing and the second wing extend perpendicular to thelight-passing region.
 13. A sleeve device for an intraoral scanner, thedevice comprising: a sleeve body configured to couple with a wand of anintraoral scanner, the sleeve body comprising a light-passing region ata distal end of the sleeve body that is configured to allownear-infrared (near-IR) light to pass; a first wing extending from thedistal end of the sleeve body adjacent to the light-passing region; asecond wing extending from the distal end of the sleeve body adjacent tothe light-passing region, wherein the first and second wings areopposite from each other and extend in a proximal to distal directionadjacent to the light-passing region; one or more near-IR light sourcesin a surface of the first wing that is opposite from a surface of thesecond wing; and one or more electrical contacts in the sleeve andconfigured to make an electrical contact with the wand to receive energyfrom the wand to power the one or more near-IR light sources.
 14. Thesleeve of claim 13, wherein the sleeve body is rigid.
 15. The sleeve ofclaim 13, wherein the sleeve comprises circuitry connected to the one ormore near-IR light sources.
 16. The sleeve of claim 13, wherein at leastone of the near-IR light sources in the first wing is at least partiallyencapsulated in the first wing to block a portion of the near-IR lightsource.
 17. The sleeve of claim 13, wherein the one or more near-IRlight sources on the first wing are between about 6.5 and 11.5 mm fromthe light-passing region at the distal end of the sleeve body.
 18. Thesleeve of claim 13, further comprising one or more additional near-IRlight sources on the second wing.
 19. The sleeve of claim 13, furthercomprising a near-IR sensor on the first wing or the second wing. 20.The sleeve of claim 13, wherein the sleeve housing is configured to beheld on a distal end of the wand by an attachment.
 21. The sleeve ofclaim 13, wherein the sleeve housing is configured to be held on adistal end of the wand by friction.
 22. The sleeve of claim 13, whereinthe light-passing region comprises an opening through the sleeve. 23.The sleeve of claim 13, wherein the first wing and the second wingextend perpendicular to the light-passing region.
 24. A sleeve devicefor an intraoral scanner, the device comprising: a sleeve bodyconfigured to fit onto the distal end of a wand of an intraoral scanner,the sleeve body comprising a light-passing region at a distal end of thesleeve body configured to allow near-infrared (near-IR) light to pass; afirst wing extending from the distal end of the sleeve body adjacent tothe light-passing region; a second wing extending from the distal end ofthe sleeve body adjacent to the light-passing region, wherein the firstand second wings are opposite from each other and extend in a proximalto distal direction adjacent to the light-passing region; one or morenear-IR light sources in a surface of the first wing that is oppositefrom a surface of the second wing; and one or more electrical contactsat a proximal end of the sleeve body and configured to make anelectrical contact with the wand to receive energy from the wand topower the one or more near-IR light sources.